Functionalized waveguide for detector system

Abstract

To provide a functionalized waveguide for a detector system.SOLUTION: The waveguide comprises: a transparent base material (6) having a front side (7) and a rear side (8). The base material has a partly transparent input coupling region (4) and a decoupling region separated therefrom in a first direction (R1). The input coupling region comprises a diffractive structure which deflects only a portion of radiation coming from an object to be detected and impinging on the front side, such that the deflected portion propagates as coupled-in radiation in the base material as far as the decoupling region via reflections and impinges on the decoupling region. The decoupling region deflects at least one portion of the coupled-in radiation impinging thereon, such that the deflected portion emerges from the base material via the front side or rear side to impinge on a detector system (2). An extent of the input coupling region in a second direction transverse to the first direction is greater than an extent of the decoupling region in the second direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a functionalized waveguide for a detector system. [Background technology]

[0002] For example, a transparent surface made of glass or plastic, such as a window or automobile windshield, comprises a transparent substrate and generally serves simply to protect a person or object from environmental influences such as wind, temperature, particles, or radiation.

[0003] There is growing interest in providing such transparent substrates that provide additional optical functionality. Summary of the Invention [Problem to be solved by the invention]

[0004] It is therefore an object of the present invention to provide a transparent substrate that has additional optical functionality. [Means for solving the problem]

[0005] The invention is defined in the independent claims. Advantageous configurations are specified in the dependent claims.

[0006] According to the functionalized waveguide of the present invention, a partially transparent in-coupling region and an out-coupling region spaced apart therefrom in a first direction are provided or embedded in a transparent substrate. The partially transparent in-coupling region may include a diffractive structure, which is used to preserve the transparency of the in-coupling region over a large angle and wavelength range during direct viewing therethrough. Therefore, only a portion of the radiation impinging on the front surface of the transparent substrate can be deflected by the transparent in-coupling region, whereby the deflected portion propagates by reflection of the radiation in-coupled into the substrate to the out-coupling region and impinges on the out-coupling region.

[0007] In this case, the transparency of the in-coupling region depends on the efficiency of in-coupling of the radiation. An increase in the in-coupling efficiency also leads to a decrease in the transparency of the in-coupling region of the functionalized waveguide. In order to obtain the highest possible transparency, the in-coupling of the radiation, for example by means of a diffractive structure (in particular at least one volume hologram), can be precisely efficient so that sufficient radiation power impinges on the out-coupling region. A partially transparent in-coupling region can be embodied such that the in-coupling efficiency is, for example, 2%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45% or 50%. In particular, the in-coupling efficiency can be in the range of 2% to 50%, whereby the transparency of the in-coupling region is in the range of 50% to 98%. The in-coupling regions of the further exemplary embodiments can also include such an in-coupling efficiency or such a transmission characteristic.

[0008] The transparent in-coupling region is preferably embodied such that the deflection of the deflected portion of the radiation impinging on the front surface of the transparent substrate is done as a pure deflection without any image generating optical function (e.g. without any focusing effect).

[0009] The reflection may in particular be total internal reflection at the front and / or rear surface of the transparent substrate, however it is also possible to provide a reflective or partially reflective layer or coating for this purpose.

[0010] The front and rear surfaces of the partially transparent substrate may be embodied as flat surfaces, in this regard the partially transparent substrate may for example be embodied as plane-parallel plates.

[0011] However, it is also possible for the front and / or rear faces to be embodied as curved.

[0012] The partially transparent substrate can be composed of glass and / or plastic. It can be monolithic or can include a multi-layer structure.

[0013] In particular, the transparent substrate may be transparent to radiation or light in the visible wavelength range, and may further be transparent to the near infrared and / or infrared range.

[0014] The out-coupling region of the transparent substrate is capable of in-coupling and deflecting at least a portion of the radiation impinging thereon, such that the deflected portion exits the substrate, preferably via the front or rear surface of the transparent substrate.

[0015] The out-coupling region can be embodied to be partially transparent. In particular, the out-coupling efficiency of the out-coupling region can be, for example, 2%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%. In particular, the out-coupling efficiency of the out-coupling region can be in the range of 2% to 50%, whereby the transparency of the out-coupling region is in the range of 50% to 98%. The out-coupling region of another exemplary embodiment can have such out-coupling efficiency or such transmission characteristics.

[0016] Partially transparent embodiments are advantageous if, for example, the in-coupling and out-coupling regions are embodied as diffractive structures (for example volume holograms). The in-coupling and out-coupling regions can, for example, be embodied in a film, which is advantageous from the standpoint of manufacturing technology.

[0017] However, it is also possible for the out-coupling region to have maximum out-coupling efficiency, which can be achieved, for example, by a reflective coating, preferably a fully reflective coating.

[0018] The in-coupling and out-coupling regions can be embodied such that they do not provide any optical imaging function other than deflection. However, the in-coupling and / or out-coupling regions can also provide an optical imaging function in addition to deflection and thus provide optical imaging. In this respect, the optical imaging function can for example realize the function of a converging or diverging lens element, a concave or convex mirror, and the curved surface can be a (centered or decentered) spherically curved or aspherically curved surface.

[0019] The diffractive structures in the in-coupling region can be realised as embedded diffractive structures, as diffractive structures between two substrates, or as diffractive structures embodied on the front or rear surface.

[0020] Additionally, the out-coupling region may include a diffractive structure, which may be embodied as an embedded diffractive structure or as a diffractive structure on the front or rear surface.

[0021] A reflection or transmission volume hologram can be provided as the diffractive structure of the in-coupling region and / or the out-coupling region. Furthermore, the diffractive structure of the out-coupling and / or the in-coupling region can also be a transmission or reflection relief grating.

[0022] The out-coupling region may further include mirrors, prisms, and / or reflective or transmissive Fresnel structures. These variations may be provided instead of or in addition to the diffractive structures of the out-coupling region.

[0023] Furthermore, a detector system is provided that includes a functionalized waveguide according to the invention (including all its developments). The detector system, also called detection system in this specification, may include a detector, on which the part of the radiation deflected by the out-coupling region impinges. The detector may be connected to the front or rear side of the substrate. In particular, it may be directly connected. The detector may be a digital image sensor (e.g. a CCD sensor or a CMOS sensor), a detector array, or for example a solar cell.

[0024] Furthermore, the detector system can be embodied in such a way that at least one optical imaging element is arranged in the region between the detector and the front and / or rear face. The at least one optical imaging element can be embodied, for example, as a lens, as a refractive lens or as a refractive camera lens. It is also possible that no imaging optics are provided in the region between the detector and the front and / or rear face. In other words, the radiation coupled out from the out-coupling region therefore impinges on the detector without passing through another optical imaging element. In this case, it is advantageous if the out-coupling region has optical imaging properties in addition to deflection.

[0025] The functionalized waveguide may be embodied such that it performs infinite-to-infinite imaging. However, it is also possible that the waveguide performs finite-to-infinite imaging, infinite-to-finite imaging, or finite-to-finite imaging.

[0026] The detector system can of course also be embodied with at least one optical imaging element arranged between the detector and the front and / or rear face. The at least one optical imaging element serves in particular to guide the part of the radiation that is deflected by the out-coupling region and can be embodied, for example, as a lens element. The at least one optical imaging element can be embodied, for example, as a lens, as a refractive lens or as a refractive camera lens.

[0027] In the case of a functionalized waveguide, the extent of the in-coupling region in a second direction transverse to the first direction can be greater than the extent of the out-coupling region in the second direction. The extent (or, for example, width) of the in-coupling region is understood in this specification to mean in particular the intended, useful, i.e. optically used, area. This is, for example, the area of ​​the in-coupling region from which the deflected radiation impinging on the detector system is emitted. The extent (or, for example, width) of the out-coupling region is understood in this specification to mean in particular the intended, useful, i.e. optically used, area. This is, for example, the area of ​​the out-coupling region from which the deflected radiation impinging on the detector system is emitted.

[0028] Additionally, the in-coupling region and the out-coupling region may be positioned so as to be centered relative to one another in the second direction.

[0029] However, it is also possible that the in-coupling region and the out-coupling region are arranged off-centre relative to each other in the second direction.

[0030] A plurality of out-coupling regions can be disposed adjacent to one another in the second direction, and at least one of the out-coupling regions can additionally include a function of deflection transverse to the first direction.

[0031] It is possible to adapt the field of view (hereinafter referred to as "FoV") of the functionalized waveguide to the FoV of the detector (or of the detector with at least one optical image generating element, e.g. a lens). This can be done in particular by adaptation of the distance between the in-coupling area and the out-coupling area along the first direction and between the extent of the in-coupling area transverse to the first direction and the extent of the out-coupling area transverse to the first direction. Adapting the FoV of the detector (or of the detector with at least one optical image generating element) to the FoV of the functionalized waveguide can be done by adaptation of the focal length of the lens and / or the size of the detector. Preferably, the FoV of the functionalized waveguide corresponds to the FoV of the detector (or of the detector with at least one optical image generating element). This can be done by targeting the FoV of the functionalized waveguide and / or by targeting the FoV of the detector (or of the detector with at least one optical image generating element).

[0032] A functionalized waveguide for an illumination and / or projection system is further provided, the waveguide comprising a transparent substrate having a front surface and a rear surface, In principle, the transparent substrate can be embodied and developed in a similar manner to the transparent substrate of the functionalized waveguide for the detector system.

[0033] In this respect, the substrate may include an in-coupling region and an out-coupling region spaced apart therefrom in a first direction, the in-coupling region deflecting at least a portion of radiation incident from a light source or image source of the illumination and / or projection system and impinging on the in-coupling region, whereby the deflected portion propagates by reflection to the out-coupling region and impinges on the out-coupling region as in-coupled radiation to the substrate. The out-coupling region may include a structure for deflecting the in-coupled radiation impinging thereon, for example a diffractive structure, whereby the deflected portion is emitted from the substrate via the front and rear surfaces. The diffractive structure may be adapted to the wavelength of radiation incident from the light source or image source, such that as much radiation as possible is reflected. Nevertheless, the diffractive structure may still have a desired transparency, for example when viewed through it. Furthermore, it is also possible for the diffractive structure to deflect only a portion of the radiation from the light source or image source.

[0034] The structures in the out-coupling region can be transmission or reflection diffractive structures, transmission or reflection volume holograms, mirrors, prisms, or transmission or reflection relief gratings.

[0035] Hence, a transparent out-coupling area is provided. The extent of the out-coupling area in a second direction transverse to the first direction may be greater than the extent of the in-coupling area in the second direction.

[0036] An illumination and / or projection system is further provided, which has a functionalized waveguide for such an illumination and / or projection system, and a light source and / or image source is additionally provided, the light from which impinges on the output coupling area.

[0037] In the case of a functionalized waveguide for a detector system, the in-coupling region may contain at least two volume holograms, each of which deflects only a portion of the radiation incident from the object to be detected and impinging on the front surface, whereby the deflected portion propagates by reflection to the out-coupling region as in-coupled radiation to the substrate and impinges on the out-coupling region. The volume holograms of the in-coupling region may differ in that their deflection functions have different spectral angular characteristics. As a result, different wavelengths can be deflected at the same angle of incidence. The out-coupling region deflects at least a portion of the in-coupled radiation impinging thereon, whereby the deflected portion leaves the substrate (preferably via the front or rear surface) and impinges on the detector system.

[0038] Such a waveguide allows more colors to be transmitted because the volume hologram in the in-coupling region has different spectral angular characteristics and therefore deflects different wavelengths at the same angle of incidence, which then become part of the in-coupled radiation to the substrate.

[0039] The volume holograms of the in-coupling area can be arranged adjacently (with or without a space between them), i.e. in particular they can be arranged adjacently in the first direction. However, the volume holograms of the in-coupling area can also be arranged on top of each other or stacked on top of each other (i.e. with a stacking direction preferably transverse to the first direction and transverse to the second direction), so that it is as if a stack of volume holograms exists. Alternatively or additionally, some or all of the functions of the volume holograms of the in-coupling area can be implemented in one volume hologram. Such an implementation is also called multiplexing. These possible configurations of the in-coupling area can be provided in all of the described exemplary embodiments.

[0040] The output coupling region can include, for each volume hologram in the input coupling region, an assigned volume hologram that provides the same spectral angular characteristics as the corresponding volume hologram in the input coupling region during deflection, thus compensating for the dispersion of the volume holograms in the input coupling region.

[0041] The volume holograms of the out-coupling area can be arranged adjacently (with or without a space between them), i.e. in particular they can be arranged adjacently in the first direction. However, the volume holograms of the out-coupling area can also be arranged on top of each other or stacked on top of each other (i.e. with a stacking direction preferably transverse to the first direction and transverse to the second direction), so that it is as if a stack of volume holograms exists. Alternatively or additionally, some or all of the functions of the volume holograms of the out-coupling area can be implemented in one volume hologram. Such an implementation is also called multiplexing. These possible configurations of the out-coupling area can be provided in all of the described exemplary embodiments.

[0042] The volume hologram of the in-coupling region can be embodied as a reflection or transmission volume hologram, the same applies to the volume hologram of the out-coupling region.

[0043] The input coupling region may include at least, or exactly, 2, 3, 4, 5, 6, 7, 8, 9, 10 up to 40, up to 50, or up to 100 (or any value between 1 and 100) volume holograms.

[0044] In the case of a functionalized waveguide for a detector system, the input coupling region may include a plurality of diffractive input coupling structures adjacent in a first direction that differ in that they have different horizontal fields of view in a plane spanning between a normal to the front surface and a second direction transverse to the first direction, whereby they deflect radiation from different horizontal fields of view towards the output coupling region.

[0045] Therefore, a larger horizontal field of view can be captured and guided to the detector.

[0046] The in-coupling diffractive structures can be embodied such that they deflect radiation from different horizontal fields towards the out-coupling region.

[0047] Therefore, a larger horizontal field of view can be captured and guided to the detector.

[0048] The in-coupling diffractive structures may be embodied such that during polarization they encode radiation from different horizontal fields of view with different polarization wavelengths, such that out-coupling and / or detection may be selective for the different horizontal fields of view.

[0049] The out-coupling region may include, for the in-coupling diffraction structure, an assigned out-coupling diffraction structure that selectively deflects radiation of the wavelength of the assigned in-coupling diffraction structure.

[0050] The out-coupling diffraction structures are able to deflect the radiation of an assigned in-coupling structure, so that said radiation impinges on locally different areas of the detector system.

[0051] At least one locally distinct area of ​​the detector may be provided with a color filter, which guides only a corresponding wavelength range to the detector.

[0052] The in-coupling diffractive structures may be embodied such that they encode radiation from different ranges of deflection angles, so that out-coupling and / or detection can be selectively performed for different horizontal fields of view.

[0053] The input coupling region may include a lamellar structure light blocking aperture in front of each input coupling diffraction structure, which defines for each input coupling diffraction structure a different vertical field of view in a plane spanning between a normal to the front surface and the first direction.

[0054] The out-coupling region can include, for each in-coupling diffraction structure, an assigned out-coupling diffraction structure that selectively deflects radiation from different deflection angle ranges of the assigned in-coupling diffraction structure. The out-coupling diffraction structures can be adjacently arranged in a first direction.

[0055] The out-coupling diffractive structure can in each case be embodied as a reflection or transmission volume hologram.

[0056] A functionalized waveguide for a detector system can be embodied or developed such that the input coupling region includes at least two different input coupling diffraction structures along the second direction, which differ in that they include different polarization components in the second direction.

[0057] There is therefore a higher efficiency in terms of utilization of the coupled-in radiation.

[0058] A deflection component in the second direction can be selected for each of the in-coupling diffractive structures, which are displaced along the second direction with respect to the out-coupling region to compensate for a current offset in the in-coupled radiation.

[0059] The out-coupling regions may be embodied to deflect radiation in-coupled by the different in-coupling diffractive structures into the same angular range.

[0060] A functionalized waveguide for a detector system may be embodied or developed such that the input coupling region includes an input coupling relief grating and the output coupling region includes an output coupling relief grating.

[0061] In particular, the input and output coupling relief gratings may have the same grating spacing.

[0062] The functionalized waveguide can also be embodied as a screen having a transparent substrate, in which case the transparent substrate can be part of the screen.

[0063] The screen can for example be a portable device (such as a smartphone or laptop), a stationary screen or any other screen mounted, for example, in a car.

[0064] The out-coupling region may be positioned closer to an edge of the substrate along a first direction than the in-coupling region.

[0065] Additionally, the in-coupling region can be located on the rear surface.

[0066] Additionally, the screen can include a light-emitting layer disposed on a rear surface of the substrate, and the in-coupling region can be disposed between the substrate and the light-emitting layer.

[0067] The image sensor may be positioned on the rear surface of the substrate in an area that serves as the viewing area of ​​the screen and that is left blank during recording by the image sensor.

[0068] The screen may include an additional camera which records the object, the recording made by the camera being later used to colorize the recording of the object by the image sensor.

[0069] The screen may comprise a light-emitting layer arranged on the rear side of the substrate, which layer generates a real image. For this purpose, the light-emitting layer may comprise, for example, light-emitting pixels. In this case, the real image is generated in the plane of the pixels. The pixels may each have an emission angle of at least 50°, 60°, 70°, 80°, 90°, 100°, 110°, 120°, 130°, 140°, 150°, 160°, 170° to less than 180°.

[0070] The pixelated light-emitting layer is disposed on the rear surface of the substrate so that light emitted by the pixels is transmitted through the substrate and reaches the viewer.

[0071] In order to prevent the light emitted from the light-emitting layer from being diffracted by the diffractive structure of the in-coupling region and therefore from reaching the observer, the diffractive structure of the in-coupling region can be designed such that only light of a certain polarization is diffracted and therefore guided within the substrate (or waveguide). The light emitted by the light-emitting layer has a polarization that is inefficient for the diffractive structure of the in-coupling region and can be transmitted unhindered by the diffractive structure of the in-coupling region. Therefore, the light-emitting layer is no longer a source of stray light and it is no longer necessary to blank or omit the pixelated light-emitting layer in that region of the in-coupling region to avoid in-coupling of stray light during recording by the image sensor.

[0072] What may be considered as defined polarization would be, inter alia, LCD displays or the application of a polarizing film between the light-emitting layer and the substrate.

[0073] The functionalized waveguide (or the aforementioned detector system) can be embodied or developed such that it is provided as a functionalized window (or as a detector system) for a vehicle. The vehicle can be a car, a truck, an airplane, a motorized or non-motorized vehicle, or any other vehicle. The window can be any window of the vehicle, such as a windshield, a side window, or a rear window. In particular, multiple windows (or detector systems) for the vehicle can be provided. These can be used, for example, to detect the position of a person or object within the vehicle. Furthermore, a vehicle including one or more such functionalized windows (or including one or more detector systems) is provided.

[0074] The out-coupling region may be positioned closer to an edge of the substrate along a first direction than the in-coupling region.

[0075] The window functionalized in this way can be used in a detector system (or detection system) that can be embodied and developed in the manner described above. In particular, a detector can be provided on which the part of the radiation deflected by the out-coupling region impinges. Between the out-coupling region and the detector, the detection system can include at least one optical imaging element. The at least one optical imaging element can be embodied, for example, as a lens, as a refractive lens or as a refractive camera lens.

[0076] The substrate may include a further in-coupling region and a further out-coupling region spaced apart therefrom in a first direction, the further in-coupling region deflecting at least a portion of the radiation incident from the light source or image source and impinging on the further in-coupling region, whereby the deflected portion propagates by reflection within the substrate to the further out-coupling region as further in-coupling radiation and impinges on the further out-coupling region. The further out-coupling region may include a structure, e.g. a diffractive structure, deflecting the further in-coupling radiation impinging thereon, whereby the deflected portion exits the substrate through the front or rear surface to provide the desired illumination and / or projection. The diffractive structure may be adapted to the wavelength of the radiation from the light source or image source, whereby as much radiation as possible is reflected. Nevertheless, the diffractive structure may still have the desired transparency, e.g. when viewed through it. It is also possible that the diffractive structure deflects only a portion of the radiation from the light source or image source.

[0077] Alternative out-coupling region structures may be transmission or reflection diffractive structures, transmission or reflection volume holograms, mirrors, prisms, or transmission or reflection relief gratings.

[0078] Hence, a window with two additional optical functions is provided.

[0079] The incoupled radiation and the incoupled further radiation may, for example, propagate in counter directions in at least some areas within the same region of the substrate, such that the same transmission channel is used for different directions.

[0080] Of course, the coupled radiation and the other coupled radiation may also propagate to completely different regions of the substrate.

[0081] The in-coupling region and the separate out-coupling region can be embodied at least partially in the same region of the substrate, they can be embodied together in an integrated manner, for example they can be embodied one above the other, and / or they can partially overlap.

[0082] Furthermore, the in-coupling region and the separate out-coupling region may be embodied in different regions of the substrate.

[0083] Furthermore, the functionalized waveguide may be embodied or developed as a functionalized window for illumination and / or projection, the substrate comprising an in-coupling region and an out-coupling region spaced apart therefrom in a first direction. The in-coupling region deflects at least a portion of the radiation incident from a light source or image source impinging on the in-coupling region, whereby the deflected portion propagates as in-coupled radiation within the substrate by reflection to the out-coupling region and impinges on the out-coupling region. The out-coupling region may comprise a structure, for example a diffractive structure, which deflects the in-coupled radiation impinging thereon, whereby the deflected portion exits the substrate (preferably via the front or rear surface) to provide the desired illumination and / or projection. The diffractive structure of the out-coupling region is preferably partially transparent. The diffractive structure may be adapted to the wavelength of the radiation incident from the light source or image source, whereby as much radiation as possible is reflected. Nevertheless, the diffractive structure may still have the desired transparency, for example when viewed through it. Furthermore, the diffractive structure may deflect only a portion of the radiation from the light source or image source.

[0084] The structures in the out-coupling region can be transmission or reflection diffractive structures, transmission or reflection volume holograms, mirrors, prisms, or transmission or reflection relief gratings.

[0085] Furthermore, the first in-coupling area for detection may have a larger horizontal extent than the first out-coupling area for detection, and the second out-coupling area for projection and / or illumination may have a larger horizontal extent and a larger vertical extent than the second in-coupling area for projection and / or illumination.

[0086] In this regard, a holographic strip for detection (no pupil replication required) and a holographic surface for projection and / or illumination can be positioned in the upper visible area of ​​the transparent substrate, and the holographic surface can generally have a larger range for eye positioning in the horizontal and vertical directions than a second input coupling area in the non-visible area of ​​the transparent substrate.

[0087] The first in-coupling region and the second out-coupling region may be in a visible region of the transparent substrate (especially if the functionalized waveguide is part of a detector system and an illumination and / or projection system).

[0088] There is further provided an illumination and / or projection system comprising a functionalized window for illumination and / or projection. The illumination and / or projection system may further comprise a light source or an image source.

[0089] The functionalized waveguide can be embodied or developed in such a way that it is suitable not only for detector systems, but also for illumination and / or projection systems. For this purpose, the substrate can comprise a second out-coupling region, which deflects at least a portion of the light from the light source or image source impinging on the second out-coupling region as illumination radiation, whereby the deflected portion serves for illumination and / or projection.

[0090] The second out-coupling region may be embodied and developed in a similar manner to the previously described out-coupling region and the respective first out-coupling region.

[0091] The waveguide can be embodied such that the substrate includes a second in-coupling region, which deflects light from the light source or image source, whereby the deflected light propagates through the substrate by reflection to a second out-coupling region, where it impinges on said second out-coupling region.

[0092] Alternatively or additionally, light from the light source or image source can impinge on the substrate as a free beam, and as a result, the light can impinge on the second out-coupling region, whereby it is not guided by reflection in the substrate.

[0093] There is further provided a detection system and an illumination and / or projection system having a functionalized waveguide for the detector system and the illumination and / or projection system. The system may include a light source or an image source.

[0094] The different embodiments of the functionalized waveguide, the functionalized screen and the functionalized window described above can be combined with each other, as long as this is technically expedient, and it is also possible to exchange individual feature groups with each other.

[0095] The detection system according to the present invention may be embodied as a camera (eg, a digital camera or a video camera).

[0096] It will be understood that the features set forth above and those to be described may be used not only in the combinations specified, but also in other combinations, or by themselves, without departing from the scope of the invention.

[0097] The present invention will be described in more detail below based on exemplary embodiments with reference to the accompanying drawings, which also disclose the essential features of the present invention. These exemplary embodiments are for illustration only and should not be construed as limiting. For example, the description of an exemplary embodiment having a plurality of elements or components should not be construed as meaning that all of these elements or components are necessary for implementation. Rather, other exemplary embodiments may also include alternative elements and components, fewer elements or components, or additional elements or components. Elements or components of different exemplary embodiments may be combined with each other unless otherwise specified. The improvements and modifications described for one of the exemplary embodiments are also applicable to other exemplary embodiments. To avoid repetition, the same elements or corresponding elements in different drawings are indicated with the same reference numerals and are not described multiple times. [Brief description of the drawings]

[0098] [Figure 1] 1 shows a side view of one embodiment of a detector system according to the present invention. [Diagram 2] 2 shows a plan view of the waveguide 1 of FIG. [Diagram 3] A top view of the waveguide 1 is shown. [Figure 4] FIG. 2 shows a schematic diagram of the spectrally resolved angle-dependent deflection efficiency of a reflection-type volume hologram in the in-coupling region 4. [Diagram 5] FIG. 1 shows a schematic diagram of the deflection efficiency for three different angles of incidence as a function of wavelength. [Figure 6] FIG. 13 shows an enlarged extract of a side view illustrating the averaging over a given angular range performed by the pixels of the detector. [Figure 7A] 1 shows a plan view of a waveguide to illustrate different width ratios between the input and output coupling regions. [Figure 7B] 1 shows a plan view of a waveguide to illustrate different width ratios between the input and output coupling regions. [Figure 7C]1 shows a plan view of a waveguide to illustrate different width ratios between the input and output coupling regions. [Figure 7D] FIG. 2 shows a top view to illustrate possible limitations of the horizontal field of view of a detector system 2 with a lens 1. [Figure 8A] 2 shows another exemplary embodiment of a waveguide 1 according to the invention. [Figure 8B] 2 shows another exemplary embodiment of a waveguide 1 according to the invention. [Figure 8C] FIG. 1 shows an enlarged side view of the out-coupling area of ​​waveguide 1 to illustrate the possibility of reducing the vertical field of view. [Figure 9A] FIG. 1 shows a diagram illustrating the fabrication of a volume hologram for the input coupling region. [Figure 9B] FIG. 1 shows a diagram illustrating the fabrication of a volume hologram for the input coupling region. [Figure 10] 1 illustrates a plan view of a waveguide according to another exemplary embodiment. [Figure 11] 11 shows a side view of the input coupling region of the waveguide of FIG. [Figure 12] FIG. 11 shows a schematic diagram of the spectrally resolved angle-dependent deflection efficiency of the in-coupling region according to FIG. [Figure 13A] 1 shows a schematic of the deflection efficiency for different angles of incidence as a function of wavelength. [Figure 13B] 1 shows a schematic of the deflection efficiency for different angles of incidence as a function of wavelength. [Figure 13C] 1 shows a schematic of the deflection efficiency for different angles of incidence as a function of wavelength. [Figure 14] 11 shows a schematic side view for illustrating the output coupling region of the waveguide according to FIG. [Figure 15] Figure 1 shows a schematic diagram of the spectrally resolved angle-dependent deflection efficiency of the in-coupling region of a waveguide with 40 different volume holograms. [Figure 16] 1 shows a plan view of a waveguide according to the present invention according to another exemplary embodiment; [Figure 17] 17 shows a top view of the waveguide of FIG. 16. [Figure 18A] FIG. 18 shows a side view of the input coupling area to explain the function of the waveguide according to FIGS. [Figure 18B] FIG. 18 shows a side view of the input coupling area to explain the function of the waveguide according to FIGS. [Figure 19] 17A and 17B show schematic diagrams of the incidence angle-dependent and spectrally dependent efficiency of mutually laterally displaced input-coupled volume holograms of a waveguide according to FIG. [Figure 20] 17A and 17B show schematic diagrams of the spectral angle dependent spectrum of an output coupling hologram of an embodiment according to FIG. 16 including spectral filtering; [Figure 21] 1 shows a side view of two different waveguides 1 to illustrate another exemplary embodiment. [Figure 22] 1 shows a side view of two different waveguides 1 to illustrate another exemplary embodiment. [Figure 23] 1 shows a side view of another embodiment of a waveguide according to the present invention; [Figure 24] FIG. 24 shows a schematic diagram of the geometric transmission spectrum of the waveguide according to FIG. [Diagram 25] FIG. 24 shows an enlarged side view of the output coupling region of the waveguide of FIG. 23. [Figure 26] 1 shows a schematic diagram of the geometric transmission spectrum in the case of vignetting by the entrance pupil of the detector system. [Figure 27] 24 shows a schematic diagram of a simulated cross section through a grating period of a waveguide embedded input coupling grating according to FIG. 23 . [Figure 28] 3 shows a schematic diagram of the diffraction efficiency of a relief grating as a function of wavelength. [Figure 29] 1 illustrates a plan view of another exemplary embodiment. [Diagram 30] 30 shows a side view of the exemplary embodiment of FIG. 29. [Diagram 31] 2 illustrates another exemplary embodiment. [Diagram 32] 32 shows a side view of FIG. 31. [Diagram 33] 1 shows a schematic diagram of an optical system. [Diagram 34] 34 shows an optical system according to FIG. 33 having a waveguide according to the invention. [Diagram 35]3 shows another exemplary embodiment of a waveguide according to the present invention that can be used in particular for projection and / or illumination. [Diagram 36] FIG. 36 shows a side view of the waveguide of FIG. [Figure 37] 36 shows a top view of the waveguide of FIG. 35. [Figure 38] 1 illustrates a schematic representation of illumination and / or projection using a waveguide. [Figure 39] 1 illustrates a schematic representation of illumination and / or projection using a waveguide. [Diagram 40] 1 illustrates a schematic representation of illumination and / or projection using a waveguide. [Figure 41A] It includes the free beam path from the light source / illumination source to the out-coupling area, and indicates illumination and / or projection where the out-coupling area is used in reflective mode. [Figure 41B] It includes the free beam path from the light source / illumination source to the out-coupling area, and indicates illumination and / or projection where the out-coupling area is used in reflection mode. [Figure 41C] It includes the free beam path from the light source / illumination source to the out-coupling area, and indicates illumination and / or projection where the out-coupling area is used in reflection mode. [Figure 42A] The corresponding arrangements according to Figures 41A to 41C are shown when the out-coupling region is used in transmission mode. [Figure 42B] The corresponding arrangements are shown in Figures 41A-41C when the out-coupling region is used in transmission mode. [Figure 42C] The corresponding arrangements according to Figures 41A to 41C are shown when the out-coupling region is used in transmission mode. [Diagram 43] 1 shows a variation of a combination of detection and projection and / or illumination. [Figure 44A] 1 shows another variant of the combination of detection with projection and / or illumination. [Figure 44B] 1 shows another variant of the combination of detection with projection and / or illumination. [Figure 44C] 1 shows another variant of the combination of detection with projection and / or illumination. [Fig.44D] 13 shows another variant of the combination of detection with illumination and / or projection. [Figure 44E] 13 shows another variant of the combination of detection with illumination and / or projection. [Fig.44F] 13 shows another variant of the combination of detection with illumination and / or projection. [Diagram 45] 1 illustrates an exemplary embodiment in which a waveguide is used in a microscope. [Figure 46A] 1 illustrates an exemplary embodiment of a waveguide incorporation or implementation in a vehicle windshield. [Figure 46B] 1 illustrates an exemplary embodiment of a waveguide incorporation or implementation in a vehicle windshield. [Figure 46C] 1 illustrates an exemplary embodiment of a waveguide incorporation or implementation in a vehicle windshield. [Figure 46D] 1 illustrates an exemplary embodiment of a waveguide incorporation or implementation in a vehicle windshield. [Figure 47A] 1 shows a variant of the incorporation of a waveguide according to the invention in a side view of a car. [Figure 47B] 1 shows a variant of the incorporation of a waveguide according to the invention in a side view of a car. [Figure 47C] 1 shows a variant of the incorporation of a waveguide according to the invention in a side view of a car. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0099] The diagrams according to FIGS. 1 to 3 show one embodiment of a waveguide 1 according to the invention together with a detector system 2 for realizing a camera 3 .

[0100] For this purpose, the waveguide 1 includes an input coupling region 4 and an output coupling region 5 spaced apart therefrom, and may be embodied on a planar-parallel plate 6 having a flat front surface 7 and a flat rear surface 8 as shown in Figures 1 to 3. The planar-parallel plate 6, which may also be referred to as substrate 6, is made of, for example, glass or plastic.

[0101] The detector system 2 and the lower part of the plate 6 with the output coupling area 5 can be arranged in a housing G, which is only shown diagrammatically in FIG. 1 so that at first glance it is not clear to the user that a camera 3 is involved.

[0102] By means of the camera 3, the object 9 can be imaged in such a way that the light beams L1, L2, L3 emanating from the object 9 enter the plate 6 via the front face 7 and are deflected by the in-coupling region 4 so that they impinge on the front face 7 at an angle which results in total internal reflection. The light beams L1, L2 and L3 are therefore guided by total internal reflection at the front face 7 and the rear face 8 to the out-coupling region 5, which provides a deflection in the direction towards the front face 7, whereby the light beams L1-L3 leave the plate via the front face 7. The light beams L1-L3 therefore propagate in the waveguide 1 from the in-coupling region 4 to the out-coupling region 5 along a first direction R1 (here the y-direction).

[0103] By means of a lens 10 of the detector system 2 the light beams L1-L3 are then focused onto a detector 11 of the detector system 2 so that a desired image of the object 9 can be recorded by the detector 11.

[0104] The in-coupling region 4 is embodied as a reflection-type volume hologram with an incidence angle-dependent wavelength selectivity, and thereby has high transmission for a large angle and wavelength range (illustrated by the transmitted light beam L1' in FIG. 1, the other transmitted light beams are not shown for simplicity of illustration). This means that only a part of the light beams L1-L3 coming from the object 9 and impinging on the in-coupling region 4 is deflected as described. The other light beams from the object 9 propagate through the in-coupling region 4 and exit the plate 6 via the rear face 8. The in-coupling region 4 can therefore be called partially transparent.

[0105] Figure 4 shows a schematic of the spectrally resolved angle-dependent deflection efficiency as a function of the incidence angle of the corresponding light beam for a reflection volume hologram in the in-coupling region 4, where the wavelength in μm is plotted along the x-axis and the incidence angle in ° is plotted along the y-axis. Figure 5 shows the deflection efficiency for incidence angles of +20°, 0° and -20°, where the wavelength in nm is plotted along the x-axis and the efficiency is plotted along the y-axis.

[0106] 4 and 5, the reflection volume hologram in the in-coupling region 4 has a wavelength of 392 nm to 398 nm (λ 中心 It can be seen that the reflector 100 can deflect radiation in the spectral range λ = 395 nm ± 3 nm with high efficiency and therefore couple it into the plane-parallel plate 6. For an angle of incidence of 0°, high efficiency is observed 中心 =532nm±4nm) for the spectral range, and for an incident angle of +20°, high input coupling efficiency is achieved from 600nm to 610nm (λ 中心 = 605 nm ± 5 nm).

[0107] The waveguide 1 according to figures 1-3 is embodied such that neither the in-coupling region 4 nor the out-coupling region 5 has an imaging function, so that there is an infinite-infinite configuration of the waveguide 1. It can also be said that the waveguide 1 performs infinite-infinite imaging. As explained with reference to figures 4 and 5, the spectral and angle-dependent deflection efficiency of the reflection volume hologram of the in-coupling region 4 therefore has the effect that each viewing angle (and therefore each point of the object 9 to be imaged) consists only of a narrow spectral range after being in-coupling by the in-coupling region 4. As a result, a spectrally resolved angular distribution is obtained, which finally results in a certain spectral profile (or colour profile) image on the detector 11. The light beams L1-L3 out-coupled by the out-coupling region 5 are therefore out-coupled with a certain angular spectrum, which is converted by the lens 10 into a position distribution on the detector 11. The detector 11 can for example be a CCD or CMOS detector.

[0108] Since the in-coupling region 4 contains a reflection volume hologram, the in-coupling through the reflection volume hologram leads to a dispersion in the in-coupling spectral range for each angle. If the out-coupling region 5 contains a reflection volume hologram embodied similarly to the in-coupling region 4, the dispersion caused by the in-coupling region 4 is compensated and all spectral components are deflected again to the corresponding angle.

[0109] As an alternative to the above-mentioned infinite-infinite configuration of the waveguide 1, the in-coupling region 4 and / or the out-coupling region 5 can have an imaging function, for example in the form of a lens element function or a concave mirror function. As a result, finite-infinite, infinite-finite or finite-finite imaging configurations can be realized by the waveguide 1. In the case of the in-coupling region 4, this can for example be used to record an object 9 that is positioned so close to the waveguide 1 that an object at infinity cannot be optically imagined. In the case of the out-coupling region 5, the implementation of such a lens element or concave mirror function makes it possible to directly convert the out-coupled angular spectrum into a position distribution in the focal plane of the lens element or mirror function thus implemented. In this case, for example, the lens 9 can be omitted. In this case, it can be said that the detector system 2 comprises the detector 11 and the lens element and / or the concave mirror function of the out-coupling region 5. Since the lens 10 can be omitted, the detector 11 can be located on the front surface 7 of the waveguide 1 and / or fixed, for example directly, thereby allowing a very high degree of integration, a minimal volume and a high robustness to be achieved.

[0110] As already explained, the spectrally resolved angular distribution after out-coupling by the out-coupling region 5 is converted into a position distribution on the detector 11 by means of an imaging function integrated into the lens 10 or the out-coupling region 5. Such a detector 11 comprises a discretization in the form of pixels. According to the example of FIG. 6 illustrating the unfolded waveguide system on the detector side, each pixel PX here has a pixel size PG, an optical axis A P and the focal length F of the image generating function of the lens 10 or of the output coupling region 5. AK The average over a specified angular range is given by

[0111] According to the example of Figures 4 and 5, the recording of the angular range is also associated with an integral over the spectral range. In this case, the spectral bandwidth is given by the maximum angle (α2 in Figure 4) and the minimum angle (α1 in Figure 4) recorded by a pixel, which can be calculated as follows:

number

number

[0112] Using these limiting angles, the bandwidth over which each pixel integrates can then be calculated, for example based on Kogelnik's coupled wave theory. The entire spectrum detected by a pixel is therefore composed of the spectrum within the detected angular range, resulting in the exemplary spectral broadening shown in Figure 5. In the limiting case where the detector 11 consists of only one pixel, through which the entire angular range is transmitted, an image formation with all spectral components will be recorded.

[0113] The position of the pupil (beam-limiting aperture, i.e. where the chief rays for all field angles intersect) is determined in the infinite-infinite configuration of the waveguide 1 by the ratio of the width B1 (extending transversely to the first direction R1 and along a second direction R2, which here corresponds to the x-direction) of the in-coupling region 4 (FIG. 2) to the width B2 of the out-coupling region 5, but the field of view of the waveguide 1 in the direction R2 additionally depends on the propagation direction R1, i.e. the distance D between the in-coupling region 4 and the out-coupling region 5 along the first direction R1 in the waveguide 1.

[0114] Of course, the dimensions of the in-coupling area 4 and the out-coupling area 5 can be limited by diaphragms. Here, the optically usable dimensions or the optically usable widths are always assumed. These are also referred to below as effective widths.

[0115] 7A, 7B, and 7C illustrate three fundamentally different width ratios of the in-coupling region 4 and the out-coupling region 5. In the analysis of the pupil position, only field angles where no vignetting occurs are considered.

[0116] 7A makes clear that when the ratio B1 / B2>1, the out-coupling region 5 of the waveguide 1 acts as a pupil. Hence, all angles are present at each position of the out-coupling region 5.

[0117] In the special case where B1 / B2=1 (FIG. 7B), only the central field angle propagates in the waveguide 1 without vignetting. In this case, both the in-coupling region 4 and the out-coupling region 5 form the pupil.

[0118] For the ratio B1 / B2<1 (FIG. 7C), the in-coupling region 4 is the pupil of the waveguide 1, so that each position of the out-coupling region 5 has a different angular range that is out-coupled.

[0119] Furthermore, in principle it is possible to plot the difference between the field of view (hereinafter also referred to as FoV) of the waveguide 1 and the field of view (hereinafter also referred to as FoV) of the detector system 2, where the smaller of the two fields of view (i.e. of the two FoVs) specifies the field of view of the entire system.

[0120] The horizontal FoV (x-direction) captured by the waveguide 1 and out-coupled back is determined by the widths B1, B2 of the in-coupling region 4 and the out-coupling region 5 and the distance D between these regions in the case of an infinity-to-infinity configuration of the waveguide 1 (irrespective of whether the pupil lies within the in-coupling region 4 and / or the out-coupling region 5). The FoV of the detector system 2 is given to a first approximation by the focal length of the lens 10 (or of the lens element function included in the out-coupling region 5) and the size of the detector 11 in the direction of the horizontal FoV.

[0121] In the ideal case, the FoVs of the waveguide 1 and the detector system 2 are the same. As a result, an optimal resolution is obtained over the entire FoV of the waveguide 1. As long as the FoV of the detector system 2 is larger than the FoV of the waveguide 1, the horizontal FoV of the entire system is given by the width of the in-coupling region 4, the width of the out-coupling region 5, and the distance D between the in-coupling region 4 and the out-coupling region 5. Advantageously, the entire FoV is therefore captured. However, the resolution is reduced. If the horizontal FoV of the detector system 2 is smaller than the FoV of the waveguide 1, the FoV of the entire system is limited by the FoV of the detector system. As a result, the advantage of improved resolution is obtained, and only a part of the FoV of the waveguide 1 is captured. When the lens 10 is used, it may happen in certain circumstances that the distance between the detector system 2 and the waveguide 1 limits the FoV, since the outer angular range cannot be captured by the lens 10, which is shown in FIG. 7D.

[0122] The desired adjustment of the FoV of the waveguide 1 to the FoV of the detector system 2 can be achieved by adaptation of B1, B2 and D. The desired adaptation of the FoV of the detector system 2 to the FoV of the waveguide 1 can be achieved by adaptation of the focal length of the lenses and / or the size of the detector.

[0123] As already explained, the position of the pupil of the waveguide 1 is defined by the ratio of the width B1 of the in-coupling region 4 to the width B2 of the out-coupling region 5. Thus, the shape of the angular distribution present in the out-coupling region 5 is altered, resulting in advantageous properties for certain configurations and applications.

[0124] If B1 / B2>1, the out-coupling region 5 forms the pupil of the waveguide 1. Considering all beams without vignetting, all viewing angles exist at each position of the out-coupling region 5. Therefore, all viewing angles, i.e. the complete FoV of the waveguide 1, can be captured with only one detector system 2 as a sufficiently large entrance pupil with a sufficiently large FoV. To achieve a large FoV of the waveguide 1, it is therefore advantageous to make the in-coupling region 4 wider than the out-coupling region 5. Furthermore, a small distance between the in-coupling region 4 and the out-coupling region 5 is advantageous.

[0125] The illustration according to FIG. 7A assumes that the in-coupling region 4 and the out-coupling region 5 are arranged symmetrically in the horizontal direction, resulting in a symmetric FoV of the waveguide 1. However, as shown in FIG. 8A, it is also possible to shift the out-coupling region 5 laterally (in the x-direction). As a result, the horizontal FoV is also shifted. Without a corresponding correction in the out-coupling region 5, this angular distribution, which is correspondingly shifted as a result of the displacement, is also generated displaced on the detector 11. This may result in the FoV of the detector system 2 being exceeded and therefore the overall FoV being constrained. This can be changed by implementing an additional deflection function (e.g. a prism, a tilted mirror or a linear grating) in the out-coupling region 5. Thus, the offset of the out-coupled angular spectrum can be compensated (or symmetrized) and the out-coupling FoV can again be matched to the FoV of the detector system 2. Alternatively, the detector system 2 can be tilted according to the angular offset. If not only one displaced output coupling area 5 is provided, but rather multiple output coupling areas 51, 52 are provided side by side with corresponding compensated and adapted detection systems 2, an extended horizontal FoV consisting of multiple individual FoVs can be generated (Figure 8B).

[0126] With this configuration it may even be possible to realise the limiting case where the total width of the out-coupling regions 5 is equal to the width of the in-coupling region 4. However, what is important is that each individual out-coupling region 5 should be considered separately with respect to the in-coupling region 4. As long as the width ratio B1 / B2>1 for each individual out-coupling region 5, each out-coupling region 5 remains a pupil of the system, so that the above relationship still holds true.

[0127] The relationships explained on the basis of the example of the horizontal position of the pupil and the horizontal FoV can likewise relate to the vertical position of the pupil and the vertical FoV, in which case the folding of the beam path in this direction should be taken into account. In the vertical direction, however, the following special properties are obtained, in which case vignetted beams are also taken into account:

[0128] In the case of an infinite-infinite configuration of the waveguide 1, the vertical FoV captured by a hypothetical waveguide system of infinite extent and delivered to the out-coupling surface is given by the critical angle of total internal reflection in the waveguide 1 and a propagation angle of less than 90° with respect to the normal to the interfaces of the waveguide, i.e. the front face 7 and the rear face 8. However, in a realistic waveguide 1 of finite extent, a propagation angle of less than 80° with respect to the normal to the front face 7 or the rear face 8 should be realized to ensure that beams L1-L3 from a large angular range propagate to the out-coupling region 5 and do not exceed it. For a normal refractive index of 1.5, therefore, an angular range of 40°-80° with respect to the normal to the front face 7 or the rear face 8 propagates in the waveguide 1 and is out-coupled again by the out-coupling region 5.

[0129] As with the horizontal FoV, the vertical FoV of the entire system (waveguide 1 and detector system 2) may also be constrained by the vertical FoV of detector system 2. Again from the angular range due to the input and output coupled spectral splitting, the spectral sensitivity of detector 11 may have a further constraining effect on the vertical FoV. For example, if detector 11 is not sensitive to particularly long and / or short wavelength radiation, the effective range of detector 11 will be reduced and therefore so will the vertical FoV of detector system 2 (FIG. 8C).

[0130] In the exemplary embodiment described above, the image on the detector contains the color profile described above, thereby making it impossible to transmit and record a full color image by the waveguide 1 .

[0131] The above-mentioned reflection-type volume holograms for the input coupling region 4 and the output coupling region 5 can be fabricated, for example, as shown in FIG. 9A, in which a photosensitive volume holographic material 12 incorporated in a waveguide 1 is exposed to a reference wave 13 having a wavelength of 532 nm incident on the front facet 7 at an incidence angle of 0° and a signal wave 14 of the same wavelength incident on the rear facet 8 at an incidence angle of 60°, the reference wave 13 and the signal wave 14 originating from the same laser, thereby generating an interference field or interference volume in the photosensitive volume holographic material, where a corresponding refractive index modulation can be formed.

[0132] Photosensitive glass, dichromated gelatin or photopolymers can be used as photosensitive volume holographic materials. These can be deposited, for example, on a PC film (polycarbonate film) and exposed there accordingly. The waveguide 1 can be produced by laminating the film to a substrate for the waveguide 1. In this case, the film can be laminated, for example, only in the areas of the in-coupling region 4 and the out-coupling region 5. Alternatively, a full lamination over the entire waveguide surface is possible, in which case the corresponding in- and out-coupling functions are only exposed in the in- and out-coupling regions. To protect the volume hologram, it is expedient to deposit another substrate on the laminated volume hologram. In this way, a laminate with the following basic structure is realized: transparent substrate, cement or adhesive layer, volume hologram, cement or adhesive layer, transparent substrate.

[0133] From the spectral angle dependence mentioned above, from an incident plane wave W1 impinging on the reflection volume hologram in the material at an angle of +20° (FIG. 9B), the spectral range of 605 nm ±5 nm is deflected towards the front surface 7, whereby the deflected wave W1 impinges on the front surface 7 at an angle β1 of about 40°. The reflection volume hologram in the input coupling region 4 transmits the remaining wavelengths of the plane wave W1.

[0134] For a plane wave W2 impinging on the reflection volume hologram at an angle of 0°, wavelengths from the range of 532 nm±4 nm are reflected so that they impinge on the front surface 7 at an angle β2 of approximately 60°. The remaining wavelengths of the plane wave W2 pass through the reflection volume hologram, thereby making the reflection volume hologram transparent to these wavelengths of the plane wave W2.

[0135] From the plane wave W3 impinging on the reflection volume hologram in the material at an angle of -20°, wavelengths of 395 nm ± 3 nm are reflected to the front surface where they impinge on the front surface at an angle β3 of approximately 80°. The remaining wavelengths of the plane wave W3 pass through the reflection volume hologram, which thereby transmits these wavelengths.

[0136] In order to achieve transmission of angular information (image information from infinity) through the waveguide 1 in the largest possible spectral range, the angle-dependent spectrum shown in Fig. 4 can be improved by an in-coupling region 4 that does not contain only one reflection volume hologram, but several reflection volume holograms 41, 42, 43, 44 and 45 arranged one below the other, as shown in Fig. 10 and Fig. 11(A)-(F). The volume holograms 41-45 differ in that they contain different spectral angular selectivities, so that for the same angle of incidence, different wavelengths are reflected by the volume holograms 41-45. Due to this angular selectivity, radiation in-coupled into the waveguide 1 by reflection onto the front surface 7, for example by the volume hologram 41, is not affected (or is only slightly affected) by the holograms 42-45 below it, so that the in-coupled radiation can propagate (to the largest possible range) unaffected to the out-coupling region 5.

[0137] The volume holograms 41-45 can also be placed one above the other in the z-direction, thus creating a stack on the waveguide. Furthermore, the functionality of all five holograms can be implemented in one hologram (or volume hologram), which is called multiplexing.

[0138] 9A, but using different wavelengths for the reference wave 12 and the signal wave 13. Alternatively, it is also possible to use the same wavelength for all volume holograms 41-45, in which case the angles of incidence of the reference wave 12 and the signal wave 13 are appropriately changed.

[0139] The reflection volume holograms 41-45 were recorded at different wavelengths using an exposure configuration according to Fig. 9 A. In this regard, the exposure wavelength is 900 nm (black) for volume hologram 41, 660 nm (red) for volume hologram 42, 532 nm (green) for volume hologram 43, 400 nm (blue) for volume hologram 44 and 370 nm (purple) for volume hologram 45.

[0140] 11(B)-11(F) show schematic diagrams of the input coupling for each of the volume holograms 41-45 over an angular range spanning a minimum angle of −20°, a maximum angle of +20°, and a central incidence angle of 0°. At 0°, in this case, each reflection volume hologram 41-45 has deflected and coupled in a spectral range around the central wavelength to which the respective reflection volume hologram 41-45 is exposed.

[0141] 12 shows a simulated total spectrum coupled to the waveguide 1 by five reflection volume holograms 41-45, similar to FIG. 4. Each reflection volume hologram 41-45 therefore contributes a different spectral range at each incidence angle. Considering the total reflection volume holograms 41-45 as a whole, the result is an increase in the spectral bandwidth at each angle, and broadband image information is ultimately preserved for all incidence angles as a whole.

[0142] Furthermore, FIG. 12 shows a shift of the input coupled spectrum towards shorter wavelengths as the angle of incidence increases, and towards longer wavelengths as the angle of incidence decreases.

[0143] FIG. 13A shows, as an example, the spectrum coupled in at an incidence angle of 0°. FIG. 13B shows the corresponding spectrum for an incidence angle of +20°, and the coupled in spectrum for an incidence angle of −20° is shown in FIG. 13C. In all the examples according to FIG. 13A-13C, the wavelength in μm is represented along the x-axis, and the coupled in efficiency in the range of 0 (no coupling in) to 1 (perfect coupling in) is represented along the y-axis. Comparison with the example according to FIG. 5 shows that the sampling of the coupled in spectrum is significantly improved by using more targeted recorded volume holograms (five reflection volume holograms versus one reflection volume hologram) compared to one reflection volume hologram.

[0144] 14 shows the corresponding reflection volume holograms 51-55 for out-coupling. The total height of the reflection volume holograms 51-55 is preferably chosen to be comparable to the entrance pupil 14 of the detector system 2, allowing to detect as much light as possible.

[0145] As in the case of the input-coupling holograms, the volume holograms 51-55 for output-coupling can also be arranged one above the other in the z-direction, resulting in a stack on the waveguide. Furthermore, it is possible to implement the functions of all five holograms in one hologram or one volume hologram, which is also called multiplexing.

[0146] To couple a virtually continuous spectrum, for example at each angle, into the waveguide 1 and thereby ensure the transmission of full-color image information, for example 40 targeted exposed reflection volume holograms can be placed one above the other. A corresponding simulation of the angle-dependent coupled spectrum is shown in FIG. The exposure wavelengths for recording individual reflection volume holograms with the exposure configuration of FIG. 9A can be selected, for example, as follows, with the wavelengths given in nm: 358, 368, 378, 389, 400, 411, 421, 432, 443, 454, 464, 474, 487, 498, 509, 519, 532, 544, 556, 568, 583, 598, 613, 629, 645, 662, 679, 696, 715, 735, 755, 775, 795, 815, 835, 855, 875, 896, 917, and 940.

[0147] Alternatively, reflection volume holograms can also be recorded at one wavelength and with adapted exposure angles of the reference wave 12 and the signal wave 13 .

[0148] After the radiation has propagated in the waveguide 1 to the out-coupling region 5, there is typically a complete spectrum present over a relatively large area, at all angles and at each position of this large out-coupling region 5. The out-coupling can then be performed with a corresponding reflection volume hologram, as described above. 40 volume holograms identical to those in the in-coupling region 4 are preferably generated.

[0149] However, since the out-coupling region 5 often does not need to be completely transmissive, any other kind of out-coupling of radiation propagated to the out-coupling region 5 is possible. In this respect, tilted mirrors, prisms, gratings with reflective coatings, transmission gratings, and / or multi-order Fresnel structures in transmission or reflection systems can be used. The use of non-transmissive optical surfaces is possible at this point in the waveguide 1, since a non-transmissive detector 11 will be provided anyway.

[0150] This possibility regarding the embodiment of the out-coupling region 5 also applies of course to the exemplary embodiments described above and to be described below.

[0151] Inclined mirrors and multi-order Fresnel structures of reflective or transmissive systems have the advantage of being highly efficient and do not introduce any additional dispersion during deflection. However, they also do not lead to dispersion compensation. Gratings and transmission gratings with reflective coatings for out-coupling can provide the desired dispersion compensation. However, they are less efficient. Prisms have high efficiency, but a disadvantage is that they can amplify the dispersion. In the case of the embodiment of the reflection volume hologram, the advantage is that the desired dispersion compensation is present, since each wavelength channel is out-coupled via a separate reflection volume hologram. However, the efficiency is relatively low, since the area of ​​the out-coupling area 5 must be divided by the number of individual reflection volume holograms.

[0152] 16-18B show exemplary embodiments of the waveguide 1 in which the horizontal FoV (i.e. the FoV in the xz plane) is expanded, assuming here that the FoV of the detector system 2 does not constrain the FoV of the waveguide 1.

[0153] The input coupling area 4 comprises three reflective volume holograms 41, 42 and 43 of the same width, arranged one above the other (in the y direction) and covering different angular ranges and therefore different horizontal fields of view in the xz plane, which is shown in angle space, especially in the top view of FIG. 17.

[0154] As an alternative to arranging the holograms 41, 42 and 43 one above the other in the y-direction, they can also be arranged one above the other in the z-direction, thus obtaining a stack above the waveguide. Furthermore, it is also possible to implement the individual holographic functions of all three holograms in one hologram (or volume hologram), which is also called multiplexing.

[0155] In this regard, for example, the second reflection volume hologram 42 can cover the angular range γ0±γ1 in the xz-plane and therefore a central field of view where γ0=0. In this case, the central field of view is given for example by the width of the second volume hologram 42, the width of the correspondingly assigned second output coupling hologram 52 and the distance between the two volume holograms 42, 52.

[0156] Compared to the second reflection volume hologram 42, the first reflection volume hologram 41 has an additional one-dimensional deflection function in the horizontal direction (in the xz plane). The horizontal field of view assigned to the first volume hologram 41 is therefore displaced by the absolute value of the applied deflection function in that angular range (angular offset) to be γ0-2·γ1±γ1. The corresponding applied deflection function for the third reflection volume hologram 43 results in a horizontal field of view of γ0+2·γ1+γ1. Different horizontal FoVs can therefore be transmitted by the combination of each volume hologram 41-43 with the corresponding volume hologram 51-53 for output combination. The absolute value and the direction of the respectively applied deflection function (angular offset) can be used to affect the total FoV in a targeted manner. In this respect, it is possible to produce, for example, a symmetric or asymmetric total FoV and FoVs with overlapping partial FoVs or gaps between the partial FoVs.

[0157] In order to achieve the largest possible, symmetrical and gap-free horizontal FoV according to FIG. 17, the implemented deflection functions should be selected in such a way that the angular ranges are adjacent to each other and have as little overlap as possible, according to the specifications in the previous section.

[0158] In the case of the exemplary embodiment described herein, all horizontal angular ranges propagate in the same horizontal channel after in-coupling, as shown in FIG. 16. This is also necessary to ensure detection by only one detection system 2. If all in-coupling holograms 41-43 are recorded identically except for the deflection function, then according to FIG. 18A, a vertical superposition also occurs. Thus, after out-coupling, all horizontal FoVs will be superposed on the detector 11. To distinguish between the individual horizontal angular ranges, in the exemplary embodiment described herein, it is made to encode the horizontal angular ranges into a corresponding number of vertical angular ranges according to FIG. 18B. In this case, care was taken to ensure that the in-coupling region 4 remains transparent for direct viewing through it at large angles and wavelength ranges. The encoding of the horizontal angular ranges into the vertical angular ranges can be made such that reflection volume holograms 41-43 are embodied in such a way that they are deflected in the waveguide 1 into different vertical propagation angular ranges. For this purpose, reflection volume holograms with corresponding deflection properties can be used. Alternatively, a lamella structure (web) - not shown - can be attached in front of each reflection volume hologram 41-43 to constrain the respective vertical FoV, however the transparency of the in-coupling region 4 is severely limited as a result.

[0159] By this distinction between different vertical propagation angle ranges, the radiation from each in-combined volume hologram 41-43, and therefore each horizontal FoV, propagates within a different vertical FoV. After out-combining, the different vertical FoVs are then transformed into mutually adjacent position distributions located laterally above and below each other on the detector 11. Hence, an expanded horizontal FoV can be captured, while the vertical FoV is reduced by the magnification factor of the horizontal FoV.

[0160] An alternative variant can use a detector-side spectral and angle-dependent separation of the horizontal FoV that is encoded into the vertical FoV, said separation being described in more detail below.

[0161] When each horizontal FoV is in-coupled with a volume hologram embodied identically apart from the deflection function (angular offset), each horizontal FoV propagates within the same vertical angle range and spectral range through the waveguide 1. For example, the incidence angle dependent spectrum approximately shown in Figure 4 results for each horizontal FoV. Detector side separation is then not possible.

[0162] However, alternatively, each horizontal FoV can be coupled into the waveguide 1 in a different direction with a particular volume hologram, with each volume hologram 41-43 recorded with a different configuration (exposure angle and / or wavelength).

[0163] Figures 19(A), 19(B) and 19(C) show the incidence angle-dependent and spectrally dependent efficiencies of laterally displaced in-coupling volume holograms 41, 42 and 43 (Figure 18B). The following discussion assumes that the vertical in-coupling angle range is constrained to ±20° by total internal reflection in the waveguide. Furthermore, detector 11 only has a spectral sensitivity from 400 nm to 700 nm. The procedure of course also applies to other vertical angle ranges and detector sensitivities.

[0164] According to the example of FIG. 19(B), the first volume hologram 41 couples radiation from the entire incidence angle range of 6.67° to 20° in the spectral range of 400 nm to 440 nm into the waveguide 1. Unlike the first volume hologram 41, the second volume hologram 42 couples radiation from the entire incidence angle range over the spectrum of 400 nm to 650 nm into the waveguide 1. The third volume hologram 43 couples radiation from the incidence angle range of −6.67° to −20° in the spectral range of 565 nm to 700 nm into the waveguide 1. Each horizontal field of view is therefore coupled into the waveguide 1 by a specific volume hologram 41 to 43 with different properties. These properties are used to separate the horizontal FoVs after output coupling.

[0165] The holograms 41, 42 and 43 can also be arranged one above the other in the z-direction, thus resulting in a stack on the waveguide. Furthermore, it is also possible to implement the individual holographic functions of all three holograms in one hologram (or volume hologram), which is also called multiplexing.

[0166] It should be expected that at each point in the out-coupling region 5 there is a spectral angular spectrum in-coupled by all of the in-coupling volume holograms 41-43. In the out-coupling region 5, volume holograms 51, 52, 53 having the same behavior as for vertical in-coupling are arranged above each other with a lateral offset. Each of said holograms 51-53 then provides an out-coupling of the radiation in-coupled by the corresponding in-coupling volume hologram 41-43 with a spectral angular distribution as shown in Figures 19(A)-19(C).

[0167] As with the in-coupling region, the holograms 51, 52, 53 can alternatively be arranged one above the other in the z-direction, thus resulting in a stack above the waveguide. Furthermore, it is also possible to implement the individual holographic functions of all three holograms in one hologram (or volume hologram), which is also called multiplexing.

[0168] After output combination, the entire field of view is separated, whereby different horizontal FoVs can be detected individually. For this purpose, first the detector area of ​​the detector 11 is divided vertically. In this case, each such area portion corresponds to a vertical angular range. In this case, the number of area portions (vertical angular ranges) is the same as the number of different horizontal FoVs. In the normal case, the detector area (entire vertical angular range) is subdivided into area portions of the same size (subdivision into area portions of different sizes is also possible). However, due to the typical behavior in reflection-type volume holograms in the individual angular ranges according to FIG. 19(C), spectral overlaps will occur, whereby different horizontal FoVs will eventually overlap with the same vertical FoV. To avoid this, a spectral filter can be provided for each partial area of ​​the detector 11, i.e. for each vertical partial angular range, which spectral filter realizes the suppression of unintended spectral components for the corresponding angular range. As a result, different horizontal FoVs can be uniquely assigned to different areas (i.e. vertical angular ranges / FoVs) on the detector. As a result, a unique allocation of different horizontal FoVs to different vertical FoVs is achieved according to FIG. 18b.

[0169] As an alternative to the use of spectral filters, it is also possible to use specific out-coupling volume holograms that provide out-coupling only in the required spectral range.

[0170] After application of a spectral filter or using a spectrally adapted output-combined volume hologram, the angle-dependent spectrum shown in Figure 20 results. Thus, no overlap of different horizontal FoVs occurs and thus there is a unique assignment of a horizontal FoV to a corresponding vertical FoV.

[0171] In this way, the detectable horizontal FoV is expanded, however at the same time this leads to a reduction in the vertical FoV.

[0172] The advantage of the above-mentioned spectral encoding of the horizontal FoV into the vertical FoV compared to the angular encoding of the horizontal FoV into the vertical FoV is primarily in the high transparency over large angles and spectral ranges when viewing directly through the in-coupling region 4.

[0173] A drawback of spectral encoding is that each horizontal FoV captures a different spectral band, which can result in lost information, for example if there is no or only little radiation in the corresponding spectral range in a particular horizontal FoV. This drawback can be compensated for by providing multiple output coupling regions whose input coupling spectra are correspondingly shifted in terms of spectrum for different horizontal FoVs. However, a corresponding number of detector systems 2 would also be required.

[0174] In the general design of the entire system of waveguides 1 and in particular the input and output coupled volume holograms the following points should be taken into account:

[0175] To achieve n different horizontal FoVs, n different input and output combined volume holograms and n angular ranges (detector areas) with corresponding bandpass or edge filter functions are required. The n horizontal angular ranges are transformed into n vertical angular ranges.

[0176] The individual efficiency profiles of the volume holograms must not contain any spectral overlap within the same angular range, since otherwise spectral separation of the vertical FoV, and therefore also of the horizontal FoV, would be impossible. Overlap of radiation components of different horizontal FoVs would occur regardless of spectral filtering.

[0177] In order to capture as much radiation power as possible, each volume hologram should be designed in such a way that the largest possible spectral range is covered in the respective covered angular range. However, the spectral sensitivity of the detector should also be taken into account here. By comparing the angle-dependent and wavelength-dependent efficiency profiles of Fig. 19(B) and 19(C), it becomes clear that only a radiation bandwidth of 40 nm is used in the angular range from +6.67° to +20°. A correspondingly optimized design of the volume holograms would make it possible to increase this bandwidth and therefore to couple in possibly higher radiation powers. In contrast to the angular range from +6.67° to +20°, in the angular range from -6.67° to -20° a spectral range of 135 nm is coupled in.

[0178] The subdivision of the horizontal FoV is related to the spectral properties of the volume hologram. In the usual case, all vertical partial FoVs have the same size. However, depending on the application, different sizes of vertical FoVs can also be realized for different horizontal FoVs. This requires a corresponding design of the volume hologram in combination with filtering upstream of the individual detector areas.

[0179] Fig. 21 shows an exemplary embodiment of a waveguide 1 in which the in-coupling region 4 is larger than the out-coupling region 5, the in-coupling region 4 being realized by a reflection volume hologram. The out-coupling region 5 may also comprise a reflection volume hologram. In this case, the FoV is given by the size of these areas and the distance between them. For the exemplary embodiment described in connection with Fig. 22, it is assumed that the FoV of the detector system 2 does not constrain the FoV of the waveguide 11.

[0180] The method according to Fig. 22 for increasing the detection efficiency subdivides the in-coupling region 4 vertically (along the second direction) into three in-coupling sub-areas 41, 42 and 43. While the central in-coupling area (i.e. the central reflective volume hologram 41) only contains the function of deflecting the radiation in a first direction (only in the y direction, no x-component) towards the out-coupling region 5, the horizontal deflection function (or the x-component of the deflection) along the second direction (towards the central volume hologram 41) is integrated in the right-hand in-coupling sub-area 42 as shown diagrammatically in Fig. 22. The corresponding horizontal deflection function along the second direction (towards the central volume hologram 41) is also integrated in the left-hand in-coupling sub-area 43.

[0181] Without this deflection function, the FoV for the input coupling area 42 and the output coupling region 5 is obtained from the size of these areas, the distance between them and the eccentricity (along the second direction) of the input coupling 42 with respect to the output coupling region 5 (the same applies to the combination of the left input coupling area 43 and the output coupling region). This FoV has an angular offset with respect to the central FoV (given by the central input coupling area 41 and the output coupling area 5). Overall, an extended FoV given by the full width of the two input coupling areas is obtained.

[0182] Said angular offset can be compensated by incorporating said deflection function in the two lateral in-coupling areas 42 and 43. The off-center in-coupling volume holograms 42, 43 then cover the same FoV as the central in-coupling volume hologram 41 in combination with the out-coupling volume hologram 5. However, the radiation leaving the off-center in-coupling volume holograms 42, 43 then propagates horizontally in the waveguide with a horizontal angular offset and is out-coupled from the waveguide 1 with said offset. Therefore, after out-coupling, the same FoVs are present next to each other. These same FoVs next to each other can be captured using a detector system 2 with a sufficiently large FoV. Therefore, the detected radiation power for the horizontal FoV increases, but the power density for the signal-to-noise ratio does not increase.

[0183] To achieve this, the output coupling area 5 is configured using volume holograms in such a way that it outputs the radiation coupled in by the central input coupling volume hologram 41 and the radiation coupled in by the off-center input coupling volume holograms 42, 43 into the same angular range.

[0184] This is achieved by the out-coupling region 5 containing different out-coupling functions that are included in the exposure. In this case, each out-coupling function is only efficient for the radiation of the corresponding in-coupling volume hologram 41-43 (angular selectivity of the volume hologram), so that finally, radiation propagating to the out-coupling region 5 from different directions is out-coupled into the same angular range by the corresponding out-coupling function. The strength of the angular selectivity can be set by the thickness and the refractive index modulation of the volume holographic material as well as the exposure configuration.

[0185] One of these functions corresponds to the initial out-coupling function and performs only vertical out-coupling of radiation. All other implemented functions have a specific, adapted angular selectivity, whereby they are only effective for a horizontal angle range around the respective horizontal angular offset, which propagates from the corresponding off-center in-coupling area 42, 43 in the direction of the out-coupling area 5. This out-coupling function includes a compensation for the horizontal angular offset in addition to the vertical out-coupling function, whereby the FoV generated by the off-center in-coupling areas 42, 43 is superimposed on the FoV generated by the central in-coupling area 41. This consequently results in a higher power density in the FoV and therefore an improved signal-to-noise ratio.

[0186] The method described herein can also be referred to in an optical sense as pupil reduction (pupil duplication during image generation or pupil dilation = see opposite optical path). In this way, power can be focused over a large area in the in-coupling region 4 and out-coupled over a smaller area in the out-coupling region 5.

[0187] It is therefore possible to realize an in-coupling area 4 with a very low efficiency and therefore a high transmission. This therefore makes it possible to capture image information with a high light intensity with an in-coupling area 4 having the highest possible transmission. On the other hand, the in-coupling area can for example be realized with an only acceptable transmission, i.e. with a high in-coupling efficiency, so that as much radiant power as possible is focused only on a very small out-coupling area. For example, very small solar cells for converting radiant energy into electrical energy can be attached to the out-coupling area. It is also possible to perform out-coupling to a detector array.

[0188] The implementation of different output coupling functions is possible with a sufficiently thick volume holographic material with a sufficiently high refractive index magnification. The implementation of different functions in only one holographic area is also called function multiplexing. Alternatively, the individual output coupling functions can also be exposed in multiple volume holographic films that are stacked on top of each other.

[0189] It should be taken into account that in the horizontal direction as well as in the vertical direction, this involves angle-dependent spectral input coupling and therefore also produces an angle-dependent spectral profile in the horizontal direction. However, when considering the vertical spectral distribution, the spectral information is lost anyway, so this color profile is not a major drawback of the method.

[0190] However, as is evident from figure 22, the increase in efficiency by vertically subdividing the in-coupling area 4 while keeping the width of the in-coupling area constant is accompanied by a reduction in the horizontal FoV. This drawback can be compensated for by combination with the variants according to figures 16-18, but this results in a reduction in the vertical FoV.

[0191] In contrast, if the in-coupling area of ​​Fig. 21 is horizontally subdivided according to Fig. 16, the initial FoV of only one in-coupling volume hologram (Fig. 21) can be enlarged. However, if the area of ​​the in-coupling volume hologram is constant, the in-coupled radiation power is not increased in this case overall. However, if the area of ​​each in-coupling volume hologram is enlarged, the efficiency of the system can be improved using the procedure described above.

[0192] Basically, the input coupling volume hologram can be freely distributed over the waveguide 1. The influence on the respective FoV of the input coupling volume hologram then needs to be taken into account and a correspondingly adapted correction of the output coupling angle range.

[0193] FIG. 23 shows an exemplary embodiment in which a relief grating is embodied in both the in-coupling region 4 and the out-coupling region 5. The rules for defining the grating spacing are substantially the same as for volume holograms. A diffraction angle is sought that ensures total internal reflection of the waveguide 1. Furthermore, symmetric gratings are advantageously used for the in- and out-coupling. Furthermore, optionally, an image generation function can be applied to the in-coupling rating and / or the out-coupling grating, as desired. Thus, even objects at a distance of, for example, 50 cm from the waveguide 1 can be sharply imaged.

[0194] The advantage of the embodiment of the input and output coupling gratings as relief structures facing the volume hologram is the low angle and wavelength selectivity. As mentioned before, when a volume hologram is used, the observation angle is associated with a restricted wavelength range. Without the embodiment according to FIG. 11, gaps in the illumination spectrum cause blind spots at the vertical observation angle. These failures can be prevented by the higher wavelength and angle acceptance of the relief structure.

[0195] The input coupling grating 20 can be molded, for example with epoxy resin or UV curable polymer, onto the right surface of the left plate 22 of thickness d1 in Figure 23. In this case, a typical polymer has a refractive index n of about 1.5.

[0196] The input coupling grating 20 is then coated with a thin high-index insulating layer 23, for which a typical refractive index is n>2.0. For example, values ​​of 10-100 nm can be used for the thickness of the layer 23. In this case, it is advantageous to coat not only the input coupling grating 20 but also the whole of the left plate 22 with the thin high-index layer 23 in order to achieve a uniform transmission impression over the whole area.

[0197] A second plate 24 (with thickness d2) is then adhesively bonded to the in-coupling grating 20 and to the associated plate 22 of thickness d1 by means of an epoxy resin or a UV-curable polymer. The in-coupling relief grating 20 is thus embedded in the substrate formed by the two plates 22 and 24 and, due to its thin high refractive index layer, acts as a reflective grating 20 with a diffraction efficiency of 5% to 20%.

[0198] For the out-coupling grating 25, a grating with the same number of lines (grating spacing) is used, which is molded on the outer surface 7 of the left plate 22 or on the outer surface 8 of the second plate 24. In the case of the exemplary embodiment shown in Fig. 23, the out-coupling grating 25 is molded on the front surface 7. Aluminum is evaporated onto this molded grating 25, which results in a high out-coupling efficiency. Efficiency figures of around 50% are achievable here over a wide wavelength and angle spectrum.

[0199] The waveguide 1 with the input coupling grating 20 and the output coupling grating 25 has two diaphragms, because the edges of the input coupling grating 20 and the edges of the output coupling grating 25 each act as diaphragms, which trim the beam path. The illustration according to Fig. 23 shows exactly one beam per wavelength. Other wavelengths emerging from the same object point are deflected by the input coupling grating 20 to different angles in the waveguide 1. This relationship between wavelength and propagation angle in the waveguide 1 is continuous but not linear.

[0200] As a result, for a long waveguide 1 with many reflections (e.g. 10, 20, etc.), it is possible that the area of ​​the input coupling grating 20 (when viewed in cross section) is directly above the output coupling grating 25. A large amount of light is then transmitted. However, it may also happen that the aperture of the input coupling grating 20 is imaged once below and once above the output coupling grating 25, such that no light is output coupled by the output coupling grating 25.

[0201] As a result, the transmitted spectrum is divided into efficient and inefficient ranges, which alternate almost periodically. Such a purely geometrically determined transmission spectrum is shown in FIG. 24, where the wavelength in nm is plotted along the x-axis and the transmission efficiency from 0 (no light incident on the input coupling grating 20 is transmitted) to 1 (all light incident on the input coupling grating 20 is out-coupled through the output coupling grating 25, regardless of the diffraction efficiency of the grating) is plotted along the y-axis. The transmission efficiency is shown for an incidence angle of -15° (dashed line), which covers the wavelength range 400-530 nm, for an incidence angle of 0° (solid line), which covers the wavelength range 440-645 nm, and for an incidence angle of +15° (dotted line), which covers the wavelength range 555 nm-690 nm. In this case, the spectral limitation arises firstly from the condition of total internal reflection and secondly from the deflection angle at which, after in-coupling, a collision with the output coupling grating still occurs (there is no total internal reflection in the outer area). From this it is clear that the interval of the transmission spectrum shifts with the angle of incidence, the interval of the transmission spectrum becoming larger as the refractive index of the waveguide 1 increases.

[0202] Figure 25 shows diagrammatically the vignetting caused by the entrance pupil EP of the detector system 2. As a result, some of the outcoupled rays may not impinge on the detector 11, resulting in a geometrically determined transmission spectrum as shown diagrammatically in Figure 26. The diagram in Figure 26 corresponds to the diagram in Figure 24. As expected, this vignetting degrades the transmission spectrum for angles of incidence of -15° and +15°.

[0203] The input coupling grating 20 can be configured as a sawtooth grating, i.e. the profile shape of each grating period at least approximately follows the shape of a sawtooth. Figure 27 shows a simulated cross section of the grating period of an embedded input coupling grating, for which a small profile rounding has been applied. A lateral range of 0-430 nm is plotted along the x-axis, and a profile cross section of the range of 0-300 nm is plotted along the y-axis, resulting in a layer thickness of about 60 nm and a blaze depth of about 120 nm. Such a structure allows a wide wavelength range to be coupled into the waveguide 1 with an efficiency of about 10-15%. The resulting diffraction efficiency (reflectance) is plotted in Figure 28 for a wavelength range of 400-650 nm (which is plotted along the x-axis). Curves RE0 and RM0 show the reflectance for the zeroth order reflection of s-polarized (RE) and p-polarized (RM) fields. Curves RM1 and RE1 show the reflectance for the minus first order diffraction of s-polarized (RE) and p-polarized (RM) fields.

[0204] A profile shape similar to that of Figure 27 can be used for the output coupling grating 25. However, here a metal coating is used instead of a highly reflective insulator.

[0205] 29 and 30 show an exemplary embodiment in which the waveguide 1 is integrated into a display 30. The display 30 can be the display of a mobile consumer device (such as a mobile phone or a laptop). It can also be the display of a stationary computer.

[0206] As is evident in the illustrations of figures 29 and 30, an in-coupling area 4 with a reflective volume hologram is embodied at the rear face 8, said hologram providing a beam deflection, whereby the deflected light rays are guided in the display, for example by total internal reflection, until they finally impinge on an out-coupling area 5 with an out-coupling volume hologram, which provides a deflection in the direction towards the camera sensor 11. The image thus recorded is as such a frontal view of a user B currently looking at the in-coupling area 4. The image therefore corresponds to a recording by a camera sensor positioned in the area of ​​the in-coupling area 4. The solution according to figures 29 and 30 can therefore be designed as a transparent image sensor, which is integrated into the display, without the display function of the display being adversely affected thereby. It is therefore possible to perform the recording of an image or an image sequence at the position of the display 30, so that a frontal view of the scene to be imaged is realised.

[0207] This property can be advantageously used, for example, for applications such as video calling or recording of a self-portrait (so-called selfie), since the gaze direction of user B towards the display coincides with the centre of the image recorded by the camera. Thus, for example, during a video call, both parties of a call can maintain more or less eye contact, which was not possible up until now because the corresponding camera was always mounted on the edge of the display. Said eye contact results in a more natural and more immersive conversation experience. When taking a self-portrait, the user can, for example, follow a live preview of the image to be recorded, without having to look away from the camera and towards the display.

[0208] In addition to the deflection function, for example the output coupling grid 5 can include an image generation function, thereby eliminating the need for an additional optical unit upstream of the camera sensor 11. In this way, the degree of integration of the camera into the display 30 can be maximized.

[0209] Due to the excellent wavelength and angle selectivity of the diffraction efficiency typical of volume holograms, and due to the ability to set the diffraction efficiency in a customized manner, the part of the display 30 covered by the input coupling grating appears largely transparent and the content displayed on the display remains visible to the observer. For that purpose, on the one hand, the efficiency of the input coupling grating 4 must be high enough to allow image acquisition on that part of the camera sensor 11. On the other hand, the efficiency of the input coupling grating must be low enough to preserve the transparency and not cause disturbing effects for the observer. The resulting transparency of the volume hologram applied in the input coupling area therefore also depends on the sensitivity to light of the used camera sensor 11.

[0210] In the simplest configuration of the in-coupling region 4 and the out-coupling region 5 according to the embodiment of figures 1-3, a different wavelength range is transmitted to the detector 11 or camera sensor 11 for each angle, thus obtaining an image with a vertical colour profile. Said image can then be converted to a monochrome image. To obtain a natural multi-coloured image, for example, the monochrome image can then be colourised in real time using image information recorded by a separate front camera. In this way, a camera function implemented by a volume hologram with the aforementioned front-view advantage can provide a natural image.

[0211] Alternatively, the color function of the camera function implemented by the volume hologram can be realized according to the exemplary embodiment of figures 10 to 15. Therefore, an additional front camera and subsequent colorization would not be necessary.

[0212] 29 and 30, it is assumed that the out-coupling area 5 and also the camera sensor 11 are located under the non-display area 31 of the display 30, because otherwise light emitted from the display would also hit the camera sensor 11, which would interfere with the recording of images.

[0213] However, if a display 30 is used that is transparent when not powered, the camera sensor can also be positioned under the area actually used by the display, as shown in the case of the exemplary embodiment according to Figures 31 and 32.

[0214] During recording of an image, the relevant area of ​​the display 30 is blanked and only light from the output coupling area 5 hits the camera sensor 11. In this way, the display 30 can only be used for display purposes when the camera function is not activated. When the camera function is activated, only parts of the display 30 are blanked. The display area is therefore only constrained to the extent necessary, and even then only near the edges.

[0215] In many applications, the ability to additionally introduce and / or detect radiation in the beam channel of an optical system can provide significant added value without significantly affecting the actual optical function of the optical system. In the case of radiation detection, radiation is reflected from the beam path at an appropriate point and directed towards a sensor. If radiation is introduced into the system, the opposite optical path is used to introduce an additional radiation component. This can be used, for example, to illuminate the object space or to introduce additional information.

[0216] In a known manner, a partially reflectively coated substrate 40 is used for this purpose, which is shown diagrammatically in Fig. 33, where two lens elements 41 and 42 for the optical system are diagrammatically drawn. This is the so-called combiner principle. However, this requires sufficient constructional space for the optical system, which is given by the size of the tilted substrate 40 or the projection beam diameter at the position of the input and / or output reflection. Furthermore, introduction and detection of radiation at the same position of the beam path is not possible without paying high costs (special coatings, complex optics for superposition of radiation).

[0217] The waveguide 1 according to the invention described above can also be used in this case, said waveguide allowing the introduction and / or detection of radiation with only minor requirements for structural space, which is shown diagrammatically in FIG.

[0218] In addition to the introduction and detection of radiation, this method also makes it possible to deliberately influence the spectral characteristics of the radiation reflected in and out by filtering. The high transparency of the waveguide 1 allows these multifunctional components to be used at virtually any position in the optical system (even on the optical axis, if necessary). Furthermore, the specific physical properties of the volume hologram make it possible to implement these functions at virtually the same position.

[0219] The aforementioned optical systems are to be understood as not only technical optical systems, but also transparent surfaces, e.g. windows, car windows, etc. In many cases, reflecting information in and out by means of a substrate with an inclined, partially reflective coating is not an acceptable solution. However, the principle of the aforementioned waveguide 1 allows these functionalities to be implemented directly on the transparent substrate (window, car window, etc.) itself, without significantly affecting the view through it, i.e. the initial beam path. This consequently gives rise to entirely novel applications for surfaces that are normally only intended to protect, e.g., people or objects from environmental influences such as wind, temperature, particles or radiation.

[0220] In this regard, the aforementioned principle of the waveguide 1 can also be used for illumination and / or projection. For this purpose, the light path in the waveguide 1 is used in the opposite direction and a static or dynamic light source (or correspondingly a luminescent image source) is used instead of a detector. As a result, the aforementioned out-coupling area becomes the in-coupling area 4 and the aforementioned in-coupling area becomes the out-coupling area 5, as shown in Figures 35, 36 and 37. Radiation from the light source 32 is in-coupled into the waveguide 1 through the in-coupling area 4 and guided in said waveguide to the out-coupling area 5, via which out-coupling takes place into a space or an optical system arranged accordingly downstream.

[0221] Projection and illumination have no fundamental difference from a physical point of view, so in both cases radiation is generally provided in a given form (angle and / or position distribution) in space or in a beam path. Illumination of an object is shown diagrammatically in Fig. 38. Fig. 39 shows diagrammatically the projection of a virtual image for observer B. Fig. 40 shows diagrammatically the projection of a real image (here letter F). The projection of a real image is the same as illumination.

[0222] The in-coupling region 4 and the out-coupling region 5 can be realized by volume holograms (preferably reflection type volume holograms), so that a virtually transparent light source or a virtually transparent projection device can be realized due to the high angle and wavelength selectivity of the volume hologram, whereby a high transfer efficiency from in-coupling to out-coupling, the generation of defined emission characteristics (i.e. angular or position distribution) and a desired spectral composition can be achieved.

[0223] In the case of a detection system, the horizontal extent of the input and output coupling areas 4, 5 can be adapted to the required FoV. In the vertical direction (or in the first direction), the size of the area is given by the size of the aperture of the detection system. To achieve a wide FoV, the extent of the input coupling area 4 in the horizontal direction (or in the second direction) should preferably be chosen to be larger than the extent of the output coupling area 5. An input coupling strip is obtained.

[0224] For projection systems, a 2D replication of the pupil is preferred to provide image information or illumination over a large area (eyebox). In this case, the pupil coupled to the substrate is replicated horizontally and vertically. The out-coupling area is therefore an area whose horizontal and vertical extent differs from that of the in-coupling area (a difference with respect to detection systems as discussed above).

[0225] When the detection and projection systems are connected, the in-coupling area of ​​the detection in the aforementioned range and the out-coupling area of ​​the projection in the aforementioned range are therefore located in the visible range of wavelengths.

[0226] Of course, also in the case of a waveguide 1 for projection and / or illumination, optical imaging functions can be assigned to the in-coupling and / or out-coupling areas 4, 5. As a result, finite-infinite, infinite-finite, finite-finite or infinite-infinite configurations of the waveguide 1 can be realized again. Thus, during the in- and / or out-coupling, the radiation propagation and also the angular distribution and / or the distribution at a given position can be deliberately influenced. In addition to or instead of optical imaging functions, for example in the form of lens elements and / or concave mirror functions, diffuser or beam transforming functions can also be introduced in the in-coupling and / or out-coupling areas, which makes it possible to deliberately influence the radiation propagation as well.

[0227] As in the detection configuration, in the illumination / projection configuration too the effective size of the input and output coupling areas 4, 5 has a large impact on the angular range that can be transported, accepted and respectively emitted by the functionalized waveguide 1.

[0228] LEDs, lasers, etc. can be used as light sources 32 and displays (e.g. DMD displays, LCD displays, etc.) can be used as image sources. Time-varying angular or position distributions can be generated by using dynamic light sources or dynamic image sources. Thus, adaptive solutions for illumination can be realized, for example in microscopes, or variable information (virtual or real image content) can be introduced into the beam path.

[0229] As an alternative to the waveguide solution, it is also possible to realize illumination and / or projection functions with high transparency over a wide angle and wavelength range in direct view through a free beam setup based on a reflection volume hologram according to Figures 41A, 41B, and 41C or based on a transmission volume hologram according to Figures 42A, 42B, and 42C.

[0230] As has already been explained many times, volume holograms exhibit angle-dependent spectral sensitivity, which property ensures that, for example, at a certain angle, radiation within a defined wavelength range is still efficiently deflected and coupled into the waveguide 1. Although this effect is rather detrimental for general detection and illumination applications, it can also be used advantageously, for example, for spectral detection or illumination applications.

[0231] In the field of illumination, this behavior of volume hologram can be used to filter out a defined spectral range in the case of directional incident radiation.In this regard, unlike lasers, which are particularly suitable for the holographic projection of virtual or real image content, for example, partially coherent narrowband light sources can be realized.In the case of convergent or divergent radiation, it is possible to use correspondingly recorded volume hologram to affect the wavelength spectrum deflected by the volume hologram by the angular distribution present in the volume hologram.

[0232] The angle-dependent spectral sensitivity of the volume hologram can also be exploited for detection applications. According to the incidence angle-dependent and spectrally dependent efficiency according to the simulation according to FIG. 4, for each incidence angle, a different spectral range is efficiently deflected, for example vertically, and in-coupled into the waveguide 1. In the simplest setup of a camera as shown in FIGS. 1-3, an out-coupling volume hologram 5 corresponding to the in-coupling volume hologram 4 is used, providing out-coupling of angles propagating in the waveguide 1, each angle being composed of a defined spectral range as a result of filtering or in-coupling. The angular distribution is then transformed by an image generating function in the out-coupling volume hologram 5 or by a lens into a position distribution on the detector 11, each position in the vertical direction then corresponds to a defined spectral range. By vertical angular scanning and simultaneous detection of the intensity on the detector 11, the angle-dependent spectral information can be determined in a parallelized manner also in the horizontal direction.

[0233] Such a system can be mounted, for example, on the underside of an aircraft. Through knowledge of the detection system 2, the flight speed and the position of the aircraft, spectral information about the overflown region can be determined, and the data is recorded horizontally in a parallelized manner.

[0234] The above-mentioned exemplary embodiments offer the possibility of functionalizing transparent surfaces, the high transparency of which can be preserved in a wide angle and wavelength range during direct viewing through them. In this case, radiation in the transparent areas is coupled by a specific volume hologram 4 into the waveguide 1 for detection and out of the waveguide 1 for illumination / projection. This propagation between the transparent detection and / or emission areas is based on total internal reflection in the substrate or the waveguide. However, reflection is also possible based on suitable reflective coatings. The optoelectronics (detectors and control sources) can then be introduced at positions that are advantageous in terms of design or function. As a result, the position of radiation detection and / or emission is not tied to the position of the optoelectronic components.

[0235] Due to the high transparency of the features introduced using the aforementioned volume holograms, these features can be realized virtually at the same location, since by suitable design of the volume hologram, these features do not or only slightly affect each other.

[0236] This can in fact be realised, for example, by a volume hologram, in which the individual functions are implemented by applying them one above the other (as a stack). Alternatively, several optical functions can be exposed in the volume hologram (with sufficient adjustment of the maximum reflectivity of the volume holographic material). Here, by a suitable design of the volume holograms 4, 5, the transparency of the functionalised waveguide 1 is preserved. In combination with the waveguide-based beam transport and the associated compact design, firstly, it is possible to realise highly functionalised transparent surfaces, for example windows. Secondly, this scheme allows the functionality of the optical system to be significantly expanded by the interference of relatively small beam paths.

[0237] Figure 43(D) shows an example of functionalization of the window 40, where the illumination (Figure 43(A)), detection (Figure 43(B)) and projection (Figure 43(C)) functions are introduced by volume holograms and the radiation transport is realized by a waveguide-based method. The different volume holograms for the input and output coupling regions are differentiated by their reflectivities: 41, 42 etc., 51, 52 etc.

[0238] Alternatively, the individual functions can also be implemented in a non-waveguide manner (ie, by free beam propagation).

[0239] Fig. 44A shows a schematic for illumination, Fig. 44B shows a schematic for detection and Fig. 44C shows a schematic for projection. However, the advantage of the structural space created by the waveguiding is lost again (at least partially) in these exemplary embodiments. Figs. 44A-44C show the implementation of the above with the respective free beam configuration using a reflection volume hologram. This is shown together with the transmission volume hologram in Figs. 44D, 44E and 44F. In Figs. 44A-44F, all the functions that are not realized by free beam propagation are implemented with a waveguide-based method.

[0240] An extension of the functionality of the optical system is shown in Fig. 45 based on illumination and detection in a microscope 45 for recording an overview of a sample. In this case, radiation is coupled into a waveguide 1 and guided to an out-coupling area 5 by a volume hologram, which then provides for out-coupling of the radiation into the projection space (sample carrier 46). Radiation backscattered from the sample 47 is then again coupled into the waveguide 1 by another volume hologram 4', which then transports the radiation up to the detector 11.

[0241] With a suitable design of the illumination system of the microscope 45, the waveguide-based system 1 can remain, for example, as a sample finder in the beam path and not interfere with the transmitted light illumination beam path. As an alternative to the arrangement shown in Fig. 45, the waveguide-based illumination and imaging system (waveguide 1) can also be mounted above the sample 47. However, in the case of a microscope, the structural space between the objective lens 48 of the microscope 45 and the sample 47 is generally highly constrained.

[0242] In both variants, the property that illumination and detection are located at the same position and on the optical axis of the microscope 45 has a positive impact on the overall functionality of the system. As a result of the perpendicular illumination of the sample 47 and the perpendicular detection of the radiation, a relatively high efficiency (detection power / illumination power) can be achieved. The projection function is provided simultaneously. This is not possible at high cost and / or without large structural space in conventional optical systems. In the case of a functionalized window 40 or a functionalized waveguide 1, comparable properties would be possible with only transparent radiation sources and detectors.

[0243] The above-described embodiments of the waveguide 1 can also be used in the field of vehicles (eg, cars, trucks, motorcycles, etc.).

[0244] In order to be able to monitor or observe the external surroundings and the interior of the vehicle, optical projection systems, such as cameras, are increasingly being installed both inside and outside. In the process of changing from the purely manual control of the vehicle by the person to automated driving through assisted driving, it should be assumed that in the future, more and more powerful detectors will be used in the automotive field to ensure a comprehensive and safe sensor system. However, these detectors must not be an obstacle to meeting aesthetic requirements, especially in the automotive field. Ideally, the sensor system is not visible to the customer or observer of the car.

[0245] Currently, optical detection systems are integrated in opaque areas, such as the B-pillar, which then only has a small opening for the lens. In order to increase design freedom and allow the occupants to have a better view outside the vehicle, the opaque areas of the vehicle body structure will be reduced in the future. Sensors, which according to conventional methods must necessarily be mounted in a specific area, can then not be integrated in a virtually invisible manner. This phenomenon is already present in optical systems for road sign and diagonal line recognition, which must necessarily be mounted in the upper central area of ​​the windshield in order to be able to determine accurate measurement data. With conventional optical systems, this results in opaque areas in the windshield, which can limit the driver's view and have a negative effect on the appearance of the vehicle. Using the aforementioned waveguides, in the future, all windows of a vehicle can be equipped with detector areas without significant loss of transparency. In this case, radiation can be coupled into the window by means of an in-coupling area provided in the window and transmitted through the waveguide to the detector, which can then be located in an opaque area of ​​the vehicle.

[0246] Figures 46A, 46B, 46C and 46D show diagrammatically different variants of realising the waveguide 1 on a windscreen 50 of a motor vehicle 51. The in-coupling region 4 can be positioned at any desired position on the windscreen 50, as it does not significantly affect the transparency of the windscreen at this position. The radiation in-coupled via the in-coupling region 4 is then guided by reflection in the windscreen 50 to the out-coupling region 5, which can be positioned in an area that is not used for viewing through. The detector system 2 (not shown) can then also be positioned in this area.

[0247] In the variant according to Fig. 46A, the out-coupling area 5 is in the area of ​​the roof of the motor vehicle. In the variant according to Fig. 46B, the out-coupling area is in the area of ​​the bonnet or dashboard. Of course, as shown in Figs. 46C and 46D, a lateral in-coupling is also possible, whereby the out-coupling area 5 is located, for example, in the area of ​​the right (Fig. 46C) or left (Fig. 46D) A-pillar. The windshield 50 (or any other transparent area) can then be functionalized with (volume) holographic and / or micro-optical relief structures in order not to significantly affect the transparency of this area in a wide wavelength and angular range during direct viewing therethrough. By means of the aforementioned functional implementation, radiation from the surroundings or from the interior of the motor vehicle is in-coupled into the windshield 50. The latter then acts as a waveguide, allowing the radiation to be propagated, for example by total internal reflection, to the out-coupling area, which then out-couples the radiation into the detector system 2. As a result, the substantially transparent surface of the windshield can be used as detection area, while the detector 11 can be mounted in a position which is advantageous in terms of design and / or function, so that the position of radiation detection and / or radiation capture is not bound by the position of the detector 11. This is particularly advantageous in cases where radiation detection necessarily has to take place at a specific position, but the latter is at the same time intended to have a high transparency.

[0248] The wavelength system described in relation to Figures 46A-46D can also be used in the reverse optical path to illuminate an object space and / or for projection purposes. In this configuration, radiation from a static or dynamic source (e.g., a light source and / or an image source) is in-coupled into the waveguide, i.e., window 50, via an out-coupling region, which in this case functions as an in-coupling region and is located in an opaque region of the vehicle, and out-coupled again using in-coupling region 4, which in this case functions as an in-coupling region and is located in a transparent region.

[0249] Of course, it is also possible to combine the aforementioned detection and the aforementioned projection and / or illumination and then embody the in-coupling and out-coupling areas arranged in the transparent areas of the windscreen close to each other or above and below each other, as already mentioned. Optimized detection can be realised, in particular in terms of spectrum and in an angle-dependent manner, for targeted adaptation of the illumination to the detection.

[0250] In the simplest structure of the waveguide 1 (infinite-infinite configuration recorded at one wavelength), it should be taken into account that in each angle of folding / guiding direction, only a certain spectral band is in-coupled into the waveguide and finally out-coupled again. If the in-coupling and out-coupling regions 4, 5 are arranged one above the other as shown for example in Figures 46A and 46B, the result is an angle- and / or position-dependent color profile in the vertical direction with respect to the road. If this arrangement is rotated ±90° (as shown in Figures 46C and 46D), the color profile is oriented horizontally (i.e. parallel to the road). Therefore, the orientation of the in-coupling region 4 with respect to the out-coupling region 5 should be carefully selected according to the respective purpose. In this case, it is also necessary to take into account the different appearance of the FoV in two mutually perpendicular directions (given by the ratio of the sizes of the in-coupling region 4 and the out-coupling region 5 and the distance between them and the spectral sensitivity of the detector).

[0251] Furthermore, the inclination of the respective window 50 and the expected position of the object to be detected should also be taken into account in the design of the in-coupling area. In this regard, for example, when observing a driver with the aid of an in-coupling area 4 introduced in the windshield, an angular deviation of the vertical FoV must be introduced in the form of a corresponding deflection function so that the vertical optical axis approximately corresponds to the area of ​​the driver's face, and for example the driver's torso is not detected. An adaptation to the expected object and its projection can therefore be made by a specific design of the in-coupling area 4. The same relationship also applies to the use of a waveguide system as illumination. Here, the out-coupling area 5 should then be adapted to the desired illumination of the object space.

[0252] The embodiment providing RGB functionality described according to figures 10-15 is advantageous for sensor systems in the automotive field in order to avoid missed detection in individual angular ranges due to the absence of spectral components. In this way it is ensured that a signal can be detected at each angle in a defined spectral range (ideally the spectral sensitivity of the detector). Furthermore, the security in terms of missed detection due to the spectral insensitivity of the in-coupling area 4 can also be increased by implementing the in-coupling and out-coupling areas 4, 5 with the above mentioned surface relief structures.

[0253] The waveguide variants for enlarging the horizontal FoV described with respect to Figures 16-20, in which the horizontal FoV is increased by encoding the vertical FoV, can advantageously be used in the automotive field, where a horizontal FoV that is much larger than the vertical FoV is often required.

[0254] The variants for increasing the detection efficiency described with reference to figures 21 and 22 can advantageously be used in the automotive sector, since a large area in the form of a window is available for the in-coupling area 4. Therefore, as much beam power as possible can be guided to the detector system 2, and also image information can be obtained in poor lighting conditions.

[0255] Furthermore, there is also the possibility of coupling in radiation outside the visible spectral range, in particular radiation from the near infrared. Using correspondingly suitable detection systems, image information can therefore also be obtained under lighting conditions that are poor for humans.

[0256] As explained with reference to Figs. 33-45, the functionalized waveguide 1 can be functionalized not only for capturing radiation, but also for illuminating the object space or for projection. For this purpose, the opposite light path is used compared to the above-mentioned detection device with the waveguide 1. In this way, the exterior and / or interior areas of the vehicle can be illuminated in a targeted manner, ensuring reliable detection even under poor lighting conditions. In this respect, failure of detection in individual angular ranges, as may occur in the case of the simplest embodiment of the waveguide 1, for example in the absence of individual spectral ranges, can be avoided. In this case, the artificial illumination and the angle-dependent spectral sensitivity of the in-coupling area should be mutually adjusted.

[0257] In the case of the windshield 50 and rear window of a motor vehicle, there is already a particularly high demand today for the detection areas in a defined position to be as transparent as possible and for the corresponding detectors or detection systems 2 to be moved into the non-transparent areas of the vehicle body. This allows a free field of vision for the driver, and optical sensors for driver assistance systems can be integrated at the same time, thereby increasing road traffic safety. In addition to the detection of the exterior area, the aforementioned functionalization also makes it possible to acquire image information from the interior of the vehicle. With the image sequences acquired in this way, in combination with corresponding data processing, further safety systems, such as, for example, fatigue recognition or gesture control, can be implemented. In this way, even without a visible opening for a camera, the identification of the driver and / or passengers is also possible.

[0258] As in the case of the windshield and rear window, also in the case of fixed side windows the frame region of the vehicle body can include the output coupling areas and detectors, here too additional functionalization can serve to obtain image information about the interior and exterior regions, without substantially affecting the transparency of the surface.

[0259] It is also possible to integrate several detection systems in different windows of the vehicle. In this way, the location can be determined as in a three-dimensional coordinate system of people and objects in space (keywords: tomography, and therefore measurements from multiple viewpoints).

[0260] The arrangement of functionalized areas and detectors can be applied to illumination designs as well, however in this case the out-coupling areas, i.e. the light emitting areas, are located in transparent areas and the in-coupling areas, including the radiation sources, are located in opaque areas.

[0261] By appropriate design of the detection and / or illumination system, the out-coupling area of ​​the illumination system can be made to match the in-coupling area of ​​the detection system.

[0262] In comparison with a fixed window, the location of the out-coupling area in the case of a displaceable window is preferably selected such that it is in an area that is not located inside the vehicle body or in an opaque area even during or after the movement. In addition, the detection system must be fixedly connected to the movable window so that the detection function is guaranteed even during or after the movement. Figures 47A-47C show various locations of the in-coupling and out-coupling areas based on the example of a movable side window.

Claims

1. A functionalized waveguide for a detector system, The waveguide (1) includes a transparent substrate (6) having a front surface (7) and a rear surface (8). The substrate (6) includes a partially transparent input coupling region (4) and an output coupling region (5) spaced therefrom in a first direction (R1), The input coupling region (4) includes a diffraction structure which deflects only a portion of the radiation incident from the object to be detected and impacting the front surface (7), thereby the deflected portion propagates through the substrate (6) by reflection to the output coupling region (5) as input coupled radiation, and impacts the output coupling region (5). The output coupling region (5) deflects at least a portion of the input coupled radiation that collides therein, thereby deflecting the portion that exits the substrate (6) through the front (7) or rear (8) and collides with the detector system (2). The range of the input coupling region (4) in the second direction (R2) that crosses the first direction (R1) is greater than the range of the output coupling region (5) in the second direction (R2). The output coupling region (5) functions as a pupil, and as a result, there is a field of view at each position of the output coupling region (5) that does not generate any vignetting.

2. The waveguide according to claim 1, wherein the larger field of view of the waveguide (1) in the second direction (R2) is provided by making the range of the input coupling region (4) in the second direction (R2) wider than the range of the output coupling region (5) in the second direction (R2).

3. The waveguide according to claim 1 or 2, wherein the output coupling region (5) includes a diffraction structure that provides an image generation optical function of a converging lens element, a diverging lens element, a concave mirror, or a convex mirror, in addition to beam deflection.

4. The waveguide according to any one of claims 1 to 3, wherein the diffraction structure of the input coupling region (4) is embodied as a reflective or transmissive volume hologram.

5. The waveguide according to any one of claims 1 to 3, wherein the diffraction structure of the input coupling region (4) is embodied as a relief grating.

6. The waveguide according to any one of claims 1 to 5, wherein the output coupling region (5) includes a reflective or transmissive volume hologram.

7. The waveguide according to any one of claims 1 to 6, wherein the output coupling region (5) includes a reflective or transmissive relief grating.

8. The waveguide according to claim 1 or 2, wherein the output coupling region (5) includes a mirror or a prism.

9. The waveguide according to claim 1 or 2, wherein the output coupling region (5) includes a reflective or transmissive Fresnel structure.

10. The waveguide according to any one of claims 1 to 9, wherein the input coupling region (4) also includes an image generation optical function in addition to the beam deflection.

11. The waveguide according to any one of claims 1 to 10, wherein the diffraction structure of the input coupling region (4) transmits a portion of the radiation incident from the object to be detected and impacting the front surface (7), thereby causing the portion to exit the substrate through the rear surface (8).

12. The waveguide according to any one of claims 1 to 11, wherein the input coupling region (4) and the output coupling region (5) are arranged so as to be centered relative to each other in the second direction (R2).

13. The waveguide according to any one of claims 1 to 11, wherein the input coupling region (4) and the output coupling region (5) are arranged such that their centers are offset from each other in the second direction (R2).

14. The waveguide according to claim 13, wherein a plurality of output coupling regions are provided that are adjacent to each other in the second direction (R2).

15. The waveguide according to claim 13, wherein at least one of the output coupling regions additionally includes a deflection function traversing the first direction (R1).

16. The waveguide according to any one of claims 1 to 15, wherein the input coupling region (4) has a transmittance of at least 50% of the radiation incident from the object to be detected and impacting the front surface (7).

17. A detector system comprising a functionalized waveguide according to any one of claims 1 to 16.

18. The detector system according to claim 17, wherein the detector system includes a detector upon which a portion of the radiation deflected by the output coupling region collides.

19. The detector system according to claim 18, wherein the detector (11) is connected to the front or rear surface (7, 8) of the substrate (6).

20. The detector system according to claim 17 or 18, wherein no other image generating optical element is disposed between the detector (11) and the front and / or rear surfaces (7, 8).

21. A functional waveguide for lighting and / or projection systems, The waveguide (1) includes a transparent substrate (6) having a front surface (7) and a rear surface (8). The substrate (6) includes an input coupling region (4) and an output coupling region (5) spaced apart therefrom in a first direction (R1), The input coupling region (4) deflects at least a portion of the radiation incident from the light source or image source of the illumination and / or projection system that collides with the input coupling region (4), thereby causing the deflected portion to propagate through the substrate (6) by reflection to the output coupling region (5) as input-coupled radiation, and collide with the output coupling region (5). The output coupling region (5) includes a diffraction structure which deflects at least a portion of the input coupled radiation that collides therein, thereby deflecting the deflected portion, which exits the substrate (6) through the front (7) or rear (8) surface. The range of the output coupling region (5) in the second direction (R2) that crosses the first direction (R1) is greater than the range of the input coupling region (4) in the second direction (R2). The output coupling region (5) functions as a pupil, and as a result, there is a field of view at each position of the output coupling region (5) that does not generate any vignetting.

22. A lighting and / or projection system having a functionalized waveguide as described in claim 21, comprising a light and / or image source wherein light from thereto collides with the input coupling region (4).

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